Polypropylene resin composition and use thereof

ABSTRACT

A polypropylene resin composition exibiting a high melt tension and superior moldability, which can be molded efficiently by a high-speed molding into scarcely deformable larger molded articles of better appearance with high stiffness and which comprises polypropylene as a main component and has the following characteristic features 1) to 4), namely, 
     1) that a melt flow rate (MFR, determined at 230° C. under a load of 2.16 kg) is in the range of 0.01 to 5 g/10 min., 
     2) that a content of a high molecular weight polypropylene exhibiting an intrinsic viscosity [η], determined at 135° C. in decalin, of 8-13 dl/g is in the range of 15 to 50% by weight, 
     3) that a gel areal density in number is 3,000/450 cm 2  or less and 
     4) that a molecular weight distribution determined by gel permeation chromatography (GPC) is 6-20, as expressed by Mw/Mn, and is 3.5 or higher, as expressed by Mz/Mw.

FIELD OF THE TECHNIQUE

The present invention relates to a polypropylene resin composition, to aprocess for the production of such resin composition and to usesthereof.

BACKGROUND OF THE TECHNIQUE

Polypropylene has widely been used in various fields includingautomobile parts, machine and electric appliances, householdcommodities, kitchen utensils and packaging films. However, problemshave been brought about in that large-sized formed articles aredifficult to obtain by, for example, extrusion molding, and in that ahigh speed molding can scarcely be attained, since polypropyleneexhibits lower melt tension (abbreviated hereinafter sometimes as MT).Concretely, the following problems have been encountered:

(1) In blow molding, a phenomenon of “draw-down” due to stretching ofthe parison by its own weight, causing decrease in the film thicknessmay be apt to occur, whereby blow molding of large-sized articles, forexample, automobile parts, such as bumper and spoiler; and others, suchas bottles, is rendered difficult.

(2) In the case of production of sheet or film by a calenderingtechnique, the resulting sheet or film may often suffer from thicknessirregularity and, in addition, it has a lower surface gloss.

(3) In the case of production of formed articles by extrusion molding, ahigh-speed molding may scarcely be practised and, in addition,large-sized extrusion-molded articles may difficultly be obtained.

(4) In the case of production of vacuum- or pressure formings from asheet by a vacuum or pressure forming technique, large-sized moldedarticles are difficult to obtain and, in addition, a deep drawing maydifficultly be incorporated.

(5) In the case of production of sheet or film by an inflation moldingtechnique, a poor surface condition may often be encountered, since thebaloon may often become unstable.

(6) In the case of producing stretched films, the resulting film may beapt to suffer from occurrence of so-called surging, so that an accidentof film breaking upon the stretching may occur and, in addition, theresulting stretched film exhibits a low thickness accuracy.

(7) In the case of producing foamed articles, foaming with a highfoaming ratio may difficultly be attained and, in addition, the cells offoamed article are large and coarse with non-uniform cell size.

In order to avoid these problems, it has heretofore been practised toemploy such polypropylene reins as given below in which the melt tensionis increased:

1) A polypropylene resin composition prepared by blending apolypropylene with a high-pressure low-density polyethylene or with ahigh-density polyethylene

2) A polypropylene resin having a widely extended molecular weightdistribution

3) A modified polypropylene resin which is obtained by slightlycross-linking a polypropylene resin using a peroxide, electronirradiation or maleic acid

4) A branched long chain polypropylene resin which is obtained byintroducing long chain branching upon the polymerization of propylene.

However, these prior art polypropylene resins having improved melttension exhibit disadvantages in that the formed article producedtherefrom reveals inferior appearance and/or lower transparency and inthat the stiffness of the resin is insufficient, though occurence ofdraw-down is made scarce for all these resins. Alternatively, if themolding temperature is elevated in order to effect a high speed molding,problems may be brought about that the resin will suffer fromdeterioration due to increased heat evolution in the resin, causinghigher trend to gel formation (fish eye formation).

In Japanese Patent Kokai Sho-59-149907 A, there is disclosed a processfor producing a polypropylene resin having higher melt tension andhigher stiffness with superior moldability by a two-stagepolymerization. This process comprises performing a 1st stagepolymerization of propylene to build up 50-85%, based on the entireweight of the final polymer product, of a polypropylene product havingan intrinsic viscosity [η] of 0.5-3.0 dl/g and, then, effecting a 2ndstage polymerization to build up 50-15%, based on the entire weight ofthe final polymer product, of a polypropylene product having anintrinsic viscosity [η] of at least 9 dl/g, to thereby produce acrystalline polypropylene resin composition having, as the entirepolypropylene resin composition, an intrinsic viscosity [η] of 2-6 dl/g,a melt flow rate (MFR) of 0.01-5 g/10 min. and an isotactic pentadfraction of 0.940 or higher.

The polypropylene resin composition produced by this process exhibits,however, a wide molecular weight distribution, as seen, for example,from the Mw/Mn values given in Examples of the specification of thisprior patent gazette in the range of 23.2-42.2, so that the moldabilityof this resin composition is worse, whereby the appearance of the moldedarticles therefrom becomes inferior. In addition, it exhibits a lowerisotactic pentad fraction, as seen in Examples of the patent gazette inthe range of 0.955-0.969, so that the stiffness of the resin isinsufficient. Moreover, the polypropylene resin composition obtained bythe above-mentioned two-stage polymerization suffers from a problem ofhigh tendency to occurrence of gel formation which causes deteriorationin the appearance of the molded article, since a polypropylene productexhibiting a low intrinsic viscosity [η] is produced in the first stagepolymerization and a polypropylene product exhibiting a high intrinsicviscosity [η] is produced in the second stage polymerization.Furthermore, when performing the above-mentioned two-stagepolymerization in a continuous way for the benefit of industrialproduction in order to produce a polypropylene product having a lowintrinsic viscosity [η] in the first stage polymerization and to producea polypropylene product having a high intrinsic viscosity [η] in thesecond stage polymerization, it is necessary to effect the first stagepolymerization of propylene in the presence of hydrogen and to realizethe second stage polymerization of propylene in the absence of hydrogen,so that it is required to reduce the excess hydrogen contained in thereaction product from the first stage polymerization as low as possibleon subjecting it to the second stage polymerization and, thus, acomplicated polymerization apparatus becomes necessary. There may occura still further problem in that a sufficiently high intrinsic viscosity[η] of the polypropylene product resulting from the second stagepolymerization is not obtained due to the presence of the unremovedhydrogen rest, which may bring about an insufficient melt tension andinsufficient stiffness.

In Japanese Patent Kokai Sho-59-172507 A, a process for producing apolypropylene resin superior in the stiffness, moldability and heatresistance by polymerizing propylene in two stages is disclosed. Thisprocess comprises producing, in one stage, 35-65%, based on the totalweight of the final resin, of a polypropylene product having anintrinsic viscosity [η] of 1.8-10 dl/g and an isotacticity of at least97.5% by weight and producing, in the other stage, 65-35%, based on thetotal weight of the final resin, of a polypropylene product having anintrinsic viscosity [η] of 0.6-1.2 dl/g and an isotacticity of at least96.5% by weight, so as to thereby obtain a polypropylene resincomposition having, as a whole, an intrinsic viscosity [η] of 1.2-7 dl/gand a molecular weight distribution expressed by Mw/Mn of 6-20. However,the intrinsic viscosity [η] of the polypropylene product of higherintrinsic viscosity [η] side, namely, higher molecular weight side, ofthe polypropylene resin composition is relatively low, as seen from thevalues given in Examples of the above patent gazette lying in the rangeof 2.10-7.28 dl/g, so that a sufficient melt tension and sufficientstiffness will not be attained, resulting thereby sometimes in aninferior appearance and insufficient strength of the molded articleproduced therefrom.

In Japanese Patent Kokai Hei-6-93034 A (corresponding to EP 573862 A2),a crystalline polypropylene resin is disclosed, which has an MIL valueof >2 g/10 min., an intrinsic viscosity [η] of ≦2.8 dl/g, an Mw/Mn valueof >20 and a 25° C. xylene-insoluble matter of ≧94 and contains afraction which has an intrinsic viscosity [η] of ≧2.6 dl/g of 10-60% byweight. It is taught that this polypropylene resin can be produced by asuccessive polymerization comprising at least two steps and is superiorin the processibility in molten state. The polypropylene resincomposition described in the above patent gazette has a defect that theappearance of the extrusion-molded or blow-molded article thereof isinferior due to its lower moldability, though it develops a high melttension, since it has an Mw/Mn value exceeding 20.

In Japanese Patent Kokai Sho-58-7439, a polypropylene resin compositionis disclosed, which is composed of 30-70% by weight of a crystallinepolypropylene having an intrinsic viscosity [η] of 0.6-3.5 dl/g and70-30% by weight of a crystalline polypropylene having an intrinsicviscosity [η] of at least 2.5 times that of the former within the rangeof 5-10 dl/g and which has, as a whole, an intrinsic viscosity [η] of4-6 dl/g. It is taught that this polypropylene resin compositionexhibits a superior moldability while maintaining superior mechanicalproperties intrinsic to crystalline polypropylene, such as stiffness,shock resistance etc., and superior physical properties, such astransparency and heat resistance, in addition to an advantageous featureof elimination of troublesome occurrence of gel formation, so that it isadapted to a hollow molding and extrusion molding. However, thispolypropylene resin composition suffers from a problem that intricatedprocess steps are required due to the necessity of melt-blending twopolypropylene resins having intrinsic viscosities [η] markedly differentfrom each other, in addition to the circumstances that the moldedarticles produced from this polypropylene resin composition is subjectto occurrence of gel formation, resulting in an inferior appearance.

An object of the present invention is to provide a polypropylene resincomposition exibiting a high melt tension and superior moldability,which can be molded efficiently by a high-speed molding into scarcelydeformable larger molded articles of better appearance with highstiffness.

Another object of the present invention is to provide a process whichcan afford to produce the above-mentioned polypropylene resincomposition in an efficient and simple manner at a lower cost.

A further object of the present invention is to provide a resincomposition to be used for blow-molding which has a high melt tensionand is superior in the moldability and which can be molded by ahigh-speed molding into scarcely deformable large-sized blow-moldedarticles of better appearance with superior stiffness.

A still further object of the present invention is to provide a scarcelydeformable blow-molded article of better appearance which is made of theabove-mentioned polypropylene resin composition or of theabove-mentioned resin composition to be used for blow-molding and whichwill scarcely suffer from occurrence of draw-down of the parison and,thus, can be produced at a high speed in an efficient manner.

A still further object of the present invention is to provide avacuum-formed or pressure-formed article made of the above-mentionedpolypropylene resin composition, which may have a large size and whichhas a better appearance with superior stiffness and can be molded by ahigh-speed molding with permission of deep drawing.

A still further object of the present invention is to provide acalendered article made of the above-mentioned polypropylene resincomposition, which may have a large size and which has a betterappearance, superior stiffness, superior gloss and scarce thicknessirregularity and can be formed by a high-speed forming.

A still further object of the present invention is to provide anextruded article made of the above-mentioned polypropylene resincomposition, wherein the said article may have a large size, allowhigh-speed forming and exhibit a better appearance and superiorstiffness.

A still further object of the present invention is to provide astretched film which is made of the above-mentioned polypropylene resincomposition and has a superior thickness accuracy, wherein the said filmmay have a large size and can be obtained by a high-speed forming in astable manner without suffering from breaking of the film duringstretching.

A still further object of the present invention is to provide a filmsuperior in the stiffness, in the appearance and in the transparencywhich is made of the above-mentioned polypropylene resin composition andis produced by inflation technique, wherein the said film may have alarge size and can be obtained by a high-speed forming under stableformation of the baloon upon the inflation molding.

A still further object of the present invention is to provide a foamedarticle which is made of the above-mentioned polypropylene resincomposition and which has a uniform and fine cellular structure with ahigh foaming ratio, wherein the said article may have a large size andcan be produced in a high-speed molding.

DISCLOSURE OF THE INVENTION

The present invention provides for the following polypropylene resincomposition and process for the production and use of such resincomposition:

(1) A polypropylene resin composition comprising polypropylene as a maincomponent and having the following characteristic features 1) to 4),namely,

1) that the melt flow rate (MFR), determined at 230° C. under a load of2.16 kg, is in the range of 0.01-5 g/10 min.,

2) that the content of a high molecular weight polypropylene exhibitingan intrinsic viscosity [η], determined at 135° C. in decalin, of 8-13dl/g is in the range of 15-50% by weight,

3) that the gel areal density in number is 3,000/450 cm² or less and

4) that the molecular weight distribution, determined by gel permeationchromatography (GPC), is in the range of 6-20 for Mw/Mn and is 3.5 orhigher for Mz/Mw.

(2) A polypropylene resin composition according to the above (1),wherein it has further the following feature 5), namely,

5) that the isotactic pentad fraction (mmmm fraction) determined by¹³C-NMR is at least 97%.

(3) A polypropylene resin composition according to the above (1) or (2),wherein it has further the following characteristic feature 6), namely,

6) that, when dividing the area underlying under the molecular weightdistribution curve on the molecular weight distribution diagram obtainedby gel permeation chromatography at the maximum peak molecular weightinto two halves, the ratio of the surface area S_(H) for the highermolecular weight side half to the surface area S_(L) for the lowermolecular weight side half, namely, S_(H)/S_(L), is at least 1.3 and theproportion of the area for the high molecular weight part havingmolecular weights of at least 1.5×10⁶ relative to the integral surfacearea underlying under the entire molecular weight distribution curve isat least 7%.

(4) A polypropylene resin composition according to either one of theabove (1) to (3), wherein it has further the following characteristicfeature 7), namely,

7) that the melt tension (MT), determined by flow tester at 230° C., isin the range of 5-30 g.

(5) A process for producing a polypropylene resin composition as definedin either one of the above (1) to (4), by polymerizing propylene by amultistage polymerization in at least two stages in the presence of apolymerization catalyst formed from

(a) a solid catalyst component based on titanium, containing magnesium,titanium, a halogen and an electron donor,

(b) a catalyst component based on organometallic compound and

(c) a catalyst component based on organosilicic compound having at leastone group selected from the group consisting of cyclopentyl,cyclopentenyl, cyclopentadienyl and derivatives of them, the saidprocess comprising,

making up, in the first polymerization stage, a high molecular weightpolypropylene product having an intrinsic viscosity [η] of 8-13 dl/g upto a proportion of 15-50% by weight with respect to the total amount ofthe finally obtained polypropylene resin composition, by polymerizingpropylene under substantial absence of hydrogen and

performing, then, in each of the second and succeeding polymerizationstages, polymerization of propylene in such a manner that apolypropylene product having an intrinsic viscosity [η] lower than 8dl/g is produced and that the melt flow rate (MFR) of the finallyobtained polypropylene resin composition, as a whole, will be in therange of 0.01-5 g/10 min.

(6) A process as defined in the above (5), wherein the polymerization ofpropylene in each polymerization stage is effected in a continuous way.

(7) A process as defined in the above (5) or (6), wherein thepolymerization of propylene in the second and succeeding polymerizationstages is effected using at least two polymerization reactors.

(8) A polypropylene resin composition comprising polypropylene as a maincomponent and having the following characteristic features 1), 2), 4),5), 7) and 8), namely,

1) that the melt flow rate (MFR), determined at 230° C. under a load of2.16 kg, is in the range of 0.01-20 g/10 min.,

2) that the content of a high molecular weight polypropylene exhibitingan intrinsic viscosity [η], determined at 135° C. in decalin, of 8-13dl/g is in the range of 20-50% by weight,

4) that the molecular weight distribution, determined by gel permeationchromatography (GPC), is in the range of 6-20 for Mw/Mn and is 4 orhigher for Mz/Mw,

5) that the isotactic pentad fraction (mmmm fraction) determined by¹³C-NMR is at least 97%,

7) that the melt tension (MT), determined by flow tester at 230° C., isin the range of 5-30 g, and

8) that the relationship between the melt tension (MT), determined byflow tester at 230° C., and the critical shearing rate (SRc) meets thefollowing formula (I)

MT>−4.16×Ln(SRc)+29  (I)

 in which MT represents the melt tension in gram, SRc represents thecritical shearing rate in sec⁻¹ and Ln indicates the natural logarithm.

(9) A polypropylene resin composition as defined in the above (8),wherein it has further the following characteristic feature 3), namely,

3) that the gel areal density in number is 3,000/450 cm² or less.

(10) A polypropylene resin composition for blow molding comprisingpolypropylene as a main component and having the followingcharacteristic features 1), 2), 4), 5), 7) and 8), namely,

1) that the melt flow rate (MFR), determined at 230° C. under a load of2.16 kg, is in the range of 0.01-20 g/10 min.,

2) that the content of a high molecular weight polypropylene exhibitingan intrinsic viscosity [η], determined at 135° C. in decalin, of 8-13dl/g is in the range of 20-50% by weight,

4) that the molecular weight distribution, determined by gel permeationchromatography (GPC), is in the range of 6-20 for Mw/Mn and is 4 orhigher for Mz/Mw,

5) that the isotactic pentad fraction (mmmm fraction) determined by¹³C-NMR is at least 97%,

7) that the melt tension (MT), determined by flow tester at 230° C., isin the range of 5-30 g, and

8) that the relationship between the melt tension (MT), determined byflow tester at 230° C., and the critical shearing rate (SRc) meets thefollowing formula (I)

 MT>−4.16×Ln(SRc)+29  (I)

 in which MT represents the melt tension in gram, SRc represents thecritical shearing rate in sec⁻¹ and Ln indicates the natural logarithm.

(11) A polypropylene resin composition as defined in either one of theabove (1) to (4) and (8) and (9), which is for blow molding.

(12) A resin composition for blow molding, comprising a polypropyleneresin composition defined in any one of the above (1) to (4) and (8) to(10).

(13) A blow-molded article produced by subjecting a resin compositiondefined in any one of the above (1) to (4) and (8) to (12) to a blowmolding.

(14) A vacuum-formed or pressure-formed article produced by subjecting apolypropylene resin composition as defined in any one of the above (1)to (4) and (8) and (9) to a vacuum- or pressure forming.

(15) A calendered article produced by subjecting a polypropylene resincomposition as defined in any one of the above (1) to (4) and (8) and(9) to a calendering.

(16) A foamed article produced by subjecting a polypropylene resincomposition as defined in any one of the above (1) to (4) and (8) and(9) to foaming.

(17) An extrusion-molded article produced by subjecting a polypropyleneresin composition as defined in any one of the above (1) to (4) and (8)and (9) to an extrusion molding.

(18) A stretched film produced by subjecting a sheet or film made of apolypropylene resin composition as defined in any one of the above (1)to (4) and (8) and (9) to a stretching.

(19) An inflation film produced by subjecting a polypropylene resincomposition as defined in any one of the above (1) to (4) and (8) and(9) to an inflation molding.

In the context of this specification, a mere denotation of “thepolypropylene resin composition according to the present invention” doescomprehend both the first and the second polypropylene resincompositions as described below.

The First Polypropylene Resin Composition

The first polypropylene resin composition according to the presentinvention comprises polypropylene as a predominant component and having,for the resin composition as a whole, the following characteristicfeatures 1), 2), 3) and 4), wherein the first polypropylene resincomposition may either comprise exclusively polypropylene or compriseother resin(s) than polypropylene in a small proportion:

1) A melt flow rate (MFR), determined in accordance with ASTM D 1238 at230° C. under a load of 2.16 kg, in the range of 0.01-5 g/10 min.,preferably 0.1-5 g/10 min., more preferably 0.3-4 g/10 min.

2) A content of a high molecular weight polypropylene having anintrinsic viscosity [η], determined at 135° C. in decalin(decahydronaphthalene), of 8-13 dl/g, preferably 8.5-12 dl/g, morepreferably 9-11 dl/g, in the range of 15-50% by weight, preferably15-40% by weight, more preferably 15-35% by weight.

3) An areal density of gel in number of 3,000 per 450 cm² or less,preferably 2,500 per 450 cm² or less, more preferably 2,000 per 450 cm²or less.

4) A molecular weight distribution, determined by gel permeationchromatography (GPC), in the range of 6-20, preferably 8-20 for Mw/Mn(weight-average molecular weight/number-average molecular weight) and of3.5 or higher, preferably in the range of 3.5-6 for Mz/Mw (z-averagemolecular weight/weight-average molecular weight).

The a real density of number of gel mentioned above is expressed by thenumber of gels per a unit film surface area (450 cm²) converted from thenumber of gels detected using a commercial gel counter on a film of 30μm thickness prepared by a T-die film-forming apparatus of 25 mmφ.

A molecular weight distribution expressed by Mw/Mn of a value in therange of 6-20 and by Mz/Mw of not lower than 3.5 does mean that thefirst polypropylene resin composition according to the present inventionhas a wider distribution in higher molecular weight ranges as comparedwith that of conventional polypropylene resin products.

For the first polypropylene resin composition according to the presentinvention, preference is given for those which have, in addition to theabove characteristic features 1) to 4), further the followingcharacteristic feature 5):

5) An isotactic pentad fraction (mmmm fraction) determined by ¹³C-NMR ofat least 97%, preferably 98.0-99.5%.

The isotactic pentad fraction (mmmm fraction) serves as a parameter ofisotacticity of polypropylene, wherein the higher this value, the higheris the isotacticity. An isotactic pentad fraction of 97% or higher doesindicate that the isotacticity of the polypropylene is high. Theabove-mentioned isotactic pentad fraction (mmmm fraction) corresponds tothe proportion of the isotactic chains as the pentad unit in thepolypropylene molecular chains, which is determined using ¹³C-NMR andwhich is the proportion of the number of propylene monomeric unitspresent in each center of the sequences of 5 monomeric propylene unitsbound each successively by meso-coupling. This can be determined in thepractice as the proportion of the mmmm peaks relative to the entireabsorption peaks within the methyl carbon region in the ¹³C-NMRspectrum.

For the first polypropylene-based resin composition according to thepresent invention, preference is given also for those which has, inaddition to the above characteristic features 1) to 4) or thefeatures 1) to 5), further the following characteristic feature 6),namely,

6) that, when dividing the area underlying under the molecular weightdistribution curve on the molecular weight distribution diagram obtainedby gel permeation chromatography at the maximum peak molecular weightinto two halves, the ratio of the surface area S_(H) for the highermolecular weight side half to the surface area S_(L) for the lowermolecular weight side half, namely, S_(H)/S_(L), is at least 1.3,preferably at least 1.35, more preferably in the range of 1.4-2, and theproportion of the area in this diagram under the molecular weightdistribution curve for the high molecular weight part of molecularweights of at least 1.5×10⁶ relative to the integral surface areaunderlying under the entire distribution curve is at least 7%,preferably 7.5% or higher, more preferably in the range of 9-40%.

The surface area on the high molecular weight side S_(H) mentioned aboveis the surface area of the higher molecular weight side half resultingwhen subdividing, on the molecular weight distribution diagram, the areaconfined between the molecular weight distribution curve prepared usinggel permeation chromatography and the axis of abscissa (molecularweight) thereof by the vertical line at the maximum peak molecularweight into two halves. The surface area S_(L) stands for the lowermolecular weight side half thereof.

The ratio of the surface area S_(H) of the higher molecular weight sidehalf to the surface area S_(L) of the lower molecular weight side half(S_(H)/S_(L)) refers to the shape of the molecular weight distributioncurve of the polypropylene product. Thus, the case of S_(H)/S_(L)>1corresponds to a molecular weight distribution curve in which a bulgingof the curve indicating existence of polymers of higher molecularweights is present on the high molecular weight side of the curve. Inthe case of S_(H)/S_(L)<1, the molecular weight distribution curve has abulging on the low molecular weight side, indicating a content of lowermolecular weight polymers. In the case of S_(H)/S_(L)=1, the molecularweight distribution curve has a shape in which the high molecular weightside and the low molecular weight side are balanced.

The proportion of the high molecular weight side half of the polymerproduct corresponds to the ratio of the surface area in the molecularweight distribution diagram for the molecular weights of 1.5×10⁶ andhigher confined between the molecular weight distribution curve and thebase line (the axis of abscissa; for the molecular weight), relative tothe entire surface area for all the molecular weights confined betweenthe molecular weight distribution curve and the base line. When thisproportion exceeds a certain definite value, it means that a polymerfraction of molecular weights higher than 1.5×10⁶ is present in thepolypropylene resin composition. At least a part of this high molecularweight fraction consists of a polymer fraction having an intrinsicviscosity [η] of 8-13 dl/g.

For the first polypropylene resin composition according to the presentinvention, preference is also given for those which have, in addition tothe above characteristic features 1) to 4), 1) to 5) or 1) to 6),further the following characteristic feature 7):

7) A melt tension (MT), determined by flow tester at 230° C., is in therange of 5-30 g, preferably 5-20 g.

The melt tension (MT) refers to a tension in molten state observed at230° C., which is determined using Flow Tester having an orifice of adiameter of 2.095 mm and a length of 8 mm by extruding the polypropyleneresin composition in molten state through the orifice of flow tester ata temperature of 230° C. at an extrusion velocity of 15 mm/min., whereinthe resin strand extruded from the orifice is guided through a pulleyprovided with a sensor and is wound up around the pulley at a velocityof 10 m/min., in order to observe the force imposed onto the pulley.

The first polypropylene resin composition according to the presentinvention provides for a high melt tension and superior in themoldability and in the stiffness, since the melt flow rate thereof is inthe above-identified specific range and the content of the highmolecular weight polypropylene fraction is in the range mentioned aboveand, in addition, the molecular weight distribution value is in theabove range.

The polypropylene constituting the predominant component of the firstpolypropylene resin composition according to the present invention maypreferably be composed exclusively of the structural unit derived frompropylene, though it may include other structural unit(s) derived fromother comonomer(s) than propylene in a small proportion, such as 10 mole% or lower, preferably 5 mole % or lower. Such other comonomer mayinclude, for example, α-olefins other than propylene, such as ethylene,1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene,1-heptene, 1-octene, 1-nonene, 1-decene and 1-dodecene; vinyl compounds,such as styrene, vinylcyclopentene, vinylcyclohexane andvinylnorbornane; vinyl esters, such as vinyl acetate and the like;unsaturated organic acids and derivatives thereof, such as maleicanhydride and the like; conjugated diene compounds; non-conjugatedpolyenes, such as dicyclopentadiene, 1,4-hexadiene, dicyclooctadiene,methylenenorbornene and 5-ethylidene-2-norbornene. Among them,preference is given to ethylene and α-olefins having 4-10 carbon atoms.They may be present as copolymers of two or more of them.

The first polypropylene resin component according to the presentinvention may contain, as a prepolymer, 0.1% by weight or less,preferably 0.05% by weight or less, of a homopolymer or copolymer ofbranched olefins, for example, 3-methyl-1-butene, 3,3-dimethyl-1-butene,3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene,3-methyl-1-hexene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene,4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene,3,5,5-trimethyl-1-hexene, vinylcyclopentane, vinylcyclohexane,vinylcycloheptane, vinylnorbornane, allylnorbornane, styrene,dimethylstyrene, allylbenzene, allyltoluene, allylnaphthalene andvinylnaphthalene. Among them, special preference is given to3-methyl-1-butene and the like.

The polypropylene constituting the first polypropylene resin compositionaccording to the present invention may also be a block-copolymer ofpropylene, which is favorable due to a possible attainment of a superiorimpact resistance in addition to a superior stiffness, wherein specialpreference is given to a propylene/ethylene block-copolymer of whichrubber part has an intrinsic viscosity [η] of 0.5-10 dl/g.

The polypropylene product constituting the first polypropylene resincomposition may preferably be produced in a multistage polymerizationwith two or more stages so as to contain propylene polymers of fromrelatively higher molecular weights to relatively lower molecularweights. In the case where the first polypropylene resin composition isconstituted exclusively of polypropylene, it is preferable to produce itin a multistage polymerization with two or more stages so as to containpropylene polymers of from relatively higher molecular weights torelatively lower molecular weights in such a way that the characteristicfeatures 1) to 4), 1) to 5), 1) to 6) or 1) to 7) described above areattained.

As a preferred process for producing the first polypropylene resincomposition according to the present invention, there may be exemplifieda process in which propylene is subjected solely or together with othercomonomer(s) to a multistage polymerization of at least two stages inthe presence of a catalyst for producing high isotactic polypropylene.Concretely, propylene is polymerized in the first stage polymerizationin the presence of a polymerization catalyst constituted of (a) a solidcatalyst component based on titanium comprising magnesium, titanium, ahalogen and an electron donor, (b) a catalyst component based onorganometallic compound and (c) a catalyst component based onorganosilicic compound having at least one substituent selected from thegroup consisting of cyclopentyl, cyclopentenyl, cyclopentadienyl andderivatives of them in substantial absence of hydrogen to produce15-50%, preferably 15-40%, more preferably 15-35%, based on the totalweight of the finally obtained entire polypropylene resin composition,of a polypropylene product of relatively higher molecular weight havingan intrinsic viscosity, determined in decalin at 135° C., of 8-13 dl/g,preferably 8.5-12 dl/g, more preferably 9-11 dl/g, whereupon apolypropylene product of relatively lower molecular weight is producedin the second and subsequent polymerization stages. The polymerizationfor producing the polypropylene product of relatively lower molecularweight produced in the second and the subsequent stages is adjusted insuch a manner that the intrinsic viscosity (η) of the polypropyleneproduct obtained will be lower than 8 dl/g (which refers to theintrinsic viscosity (η) of the entire polypropylene resin compositionincluding all those which are produced in the stages preceding thereto)and the melt flow rate (MFR) of the finally obtained polypropylene resincomposition, as a whole, will be in the range of 0.01-5 g/10 min.,preferably 0.1-5 g/10 min., more preferably 0.3-4 g/10 min. For thepractical way for adjusting the intrinsic viscosity (η) of thepolypropylene produced in the second or subsequent stage, there is nospecial limitation, while it is preferable to use hydrogen as themolecular weight regulator.

As the sequential order of the production, it is preferable to producethe polypropylene of relatively higher molecular weight in the firststage under substantial absence of hydrogen and to produce then, in thesecond or subsequent stage(s), the polypropylene of relatively lowermolecular weight. While it may be possible to reverse the polymerizationorder, it should be necessary therefor to incorporate exhaustiveelimination of the molecular weight regulator, such as hydrogen,included in the first stage reaction product before the initiation ofpolymerization in the second or subsequent stage(s), in order to producea polypropylene product of relatively lower molecular weight in thefirst stage and to produce polypropylene product(s) of relatively highermolecular weight in the second and the subsequent stages, so thatemployment of an intricated apparatus becomes necessary and attainmentof increase in the intrinsic viscosity [η] of the polypropylene productin the second and the subsequent stages may not be easy.

The polymerization in each stage may be realized either continuously orin a batchwise process. The polymerization may be performed in a knownpractice, for example, by slurry polymerization or bulk polymerization.The polymerization in the second and the subsequent stages maypreferably be carried out subsequently to the first stage polymerizationin a continuous manner. When a batch process is employed, the multistagepolymerization can be effected in one single reactor.

While it is favorable to carry out the polymerization of propylene ineach stage in a continuous manner in order to produce the firstpolypropylene resin composition according to the present invention in anefficient and economical way, a continuous polymerization may oftenbring about occurrence of gel formation. In order to suppress gelformation as scarce as possible, it is favorable to carry out theproduction of the polypropylene product of relatively lower molecularweight in the second and the subsequent stages using at least twopolymerization reactors, preferably at least three reactors in acontinuous manner in each reactor and to perform transference of thepolymerization product from a reactor to another reactor also in acontinuous way. By performing the production of polypropylene productsin the second and the subsequent stages continuously using a pluralityof reactors, a polypropylene resin composition exhibiting scarceoccurrence of gel formation can be obtained.

The Second Polypropylene Resin Composition

The second polypropylene resin composition according to the presentinvention comprises polypropylene as a main component and has, for theresin composition as a whole, the characteristic features 1), 2), 4),5), 7) and 8) given below. The second polypropylene resin compositionmay either be constituted exclusively of polypropylene or contain otherresin(s) than polypropylene in a small proportion.

1) A melt flow rate (MFR), determined according to ASTM D1238 at 230° C.under a load of 2.16 kg, in the range of 0.01-20 g/10 min., preferably0.05 -10 g/10 min.

2) A content of a high molecular weight part polypropylene having anintrinsic viscosity [η], determined at 135° C. in decalin, of 8-13 dl/g,preferably of 8.5-12 dl/g, in the range of 20-50% by weight, preferably25-45% by weight.

4) A molecular weight distribution, determined by gel permeationchromatography (GPC), in the range of 6-20, preferably 6-13 for Mw/Mn(weight-average molecular weight/number-average molecular weight) and 4or higher, preferably in the range of 4-7 for Mz/Mw (z-average molecularweight/weight-average molecular weight).

5) An isotactic pentad fraction (mmmm fraction), determined by 13C-NMR,of at least 97%, preferably in the range of 98.0-99.5%.

7) A melt tension (MT), determined by flow tester at 230° C., in therange of 5-30 g, preferably 8-30 g.

8) A relationship between the melt tension (MT), determined by flowtester at 230° C., and the critical shearing rate (SRc) satisfying thefollowing formula (I) or, preferably, following formula (I′), namely,

MT>−4.16×Ln(SRc)+29  (I)

MT>−4.16×Ln(SRc)+33  (I′)

 in which MT represents the melt tension in gram, SRc represents thecritical shearing rate in sec⁻¹ and Ln indicates the natural logarithm.

The isotactic pentad fraction (mmmm fraction) and the melt tension (MT)can be determined in the same method as described previously in thedisclosure of the first polypropylene resin composition. The criticalshearing rate (SRc) represents the shearing velocity at which meltfracture commences and can be determined using Flow Tester provided withan orifice having a diameter of 1 mm and a length of 10.9 mm byextruding the molten polypropylene resin composition through the orificeat a temperature of 230° C. at an extrusion velocity of 0.5 mm/min.under successive increase of the extrusion velocity, in order to observethe extrusion velocity at which melt fracture of the extruded strandbegins to occur.

The molecular weight distribution expressed by an Mw/Mn value of 6-20and an Mz/Mw value of 4 or higher indicates that the moleculardistribution of the second polypropylene resin composition according tothe present invention is more widely shifted towards high molecularweight side as compared with ordinary polypropylene product.

For the second polypropylene resin composition according to the presentinvention, preference is given to those which have further, in additionto the characteristic features 1), 2), 4), 5), 7) and 8), the followingcharacteristic feature 3):

3) A gel areal density, as determined by the method explainedpreviously, in number of 3,000/450 cm² or less, preferably 2,500/450 cm²or less, more preferably 2,000/450 cm² or less.

The second polypropylene resin composition according to the presentinvention has a high melt tension and is superior in the moldability andin the stiffness as well, since the molecular weight distribution iswithin the specific range as above and the melt tension is in a specificrelation with the critical shearing rate.

The polypropylene product to be present as the main component of thesecond polypropylene resin composition according to the presentinvention may preferably be composed exclusively of the structural unitderived from propylene, though it may include other structural unit(s)derived from other comonomer(s) than propylene in a small proportion,such as 10 mole % or lower, preferably 5 mole % or lower. Such othercomonomer may include, for example, α-olefins other than propylene, suchas ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene,3-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene and1-dodecene; vinyl compounds, such as styrene, vinylcyclopentene,vinylcyclohexane and vinylnorbornane; vinyl esters, such as vinylacetate and the like; unsaturated organic acids and derivatives thereof,such as maleic anhydride and the like; conjugated diene compounds;non-conjugated polyenes, such as dicyclopentadiene, 1,4-hexadiene,dicyclooctadiene, methylenenorbornene and 5-ethylidene-2-norbornene.Among them, preference is given to ethylene and α-olefins having 4-10carbon atoms. They may be present as copolymers of two or more of them.

The second polypropylene resin component according to the presentinvention may contain, as a prepolymer, 0.1% by weight or less,preferably 0.05% by weight or less, of a homopolymer or copolymer ofbranched olefins, for example, 3-methyl-1-butene, 3,3-dimethyl-1-butene,3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene,3-methyl-1-hexene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene,4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene,3,5,5-trimethyl-1-hexene, vinylcyclopentane, vinylcyclohexane,vinylcycloheptane, vinylnorbornane, allylnorbornane, styrene,dimethylstyrene, allylbenzene, allyltoluene, allylnaphthalene andvinylnaphthalene. Among them, special preference is given to3-methyl-1-butene and the like.

The polypropylene constituting the second polypropylene resincomposition according to the present invention may also be ablock-copolymer of propylene, which is favorable due to a possibleattainment of a superior impact resistance in addition to a superiorstiffness, wherein special preference is given to a propylene/ethyleneblock-copolymer of which rubber part has an intrinsic viscosity [η] of0.5-10 dl/g.

For the polypropylene product constituting the second polypropyleneresin composition according to the present invention, a polypropyleneproduct exhibiting the characteristic features 1), 2), 4), 5), 7) and 8)or the characteristic features 1) to 5), 7) and 8) may be employed assuch therefor, so long as it can be produced within a single stagepolymerization, while the polypropylene product comprises polymers ofwidespread molecular weights from relatively lower ones to relativelyhigher ones. While it is permissible here to produce polypropyleneproducts having different molecular weights separately and blend them bymelt-mixing, it is preferable to produce polypropylene products havingdifferent molecular weights in a multi-stage polymerization of at leasttwo stages to thereby obtain a product comprising polymers of widevariety of molecular weights of relatively lower to relatively higherones. While it is permissible to produce the polypropylene products ofrelatively higher molecular weights and the polypropylene products ofrelatively lower molecular weights separately but not in a multistagepolymerization and, then, to blend them together by melt mixing, thiscauses a tendency to gel-formation and is not favorable. For a favorablepractice for producing the second polypropylene resin compositionaccording to the present invention, there may be exemplified a processin which propylene is polymerized alone or together with othercomonomer(s) in the presence of a catalyst for producing stereospecificpolypropylene in a multistage polymerization of at least two stages.

As a concrete practice for realizing multistage polymerization, theremay be exemplified a process of two-stage polymerization, whichcomprises

producing, in a first stage, 20-50%, preferably 25-45%, based on theweight of the finally obtained polypropylene resin composition as awhole, of a polypropylene product of relatively higher molecular weighthaving an intrinsic viscosity [η], determined at 135° C. in decalin, of8-13 dl/g, preferably 8.5-12 dl/g, and

producing, in a second stage, 50-80%, preferably 55-75%, based on theweight of the finally obtained polypropylene resin composition as awhole, of a polypropylene product of relatively lower molecular weighthaving an intrinsic viscosity [η] (this intrinsic viscosity [η] refersto the intrinsic viscosity [η] of the polypropylene product produced inthe second stage solely containing no polypropylene product produced inthe first stage) of 0.8-4 dl/g.

There may also be exemplified alternatively a process of three-stagepolymerization for producing the second polypropylene resin compositionaccording to the present invention, which comprises

producing, in the first stage, 20-50%, preferably 25-45%, based on theweight of the finally obtained polypropylene resin composition as awhole, of a polypropylene product of relatively higher molecular weighthaving an intrinsic viscosity [η], determined at 135° C. in decalin, of8-13 dl/g, preferably 8.5-12 dl/g, and

producing, in the second stage, a polypropylene product in such a mannerthat the intrinsic viscosity [η] of the entire product as a whole (thisintrinsic viscosity [η] refers to the intrinsic viscosity [η] of theentire polypropylene product containing the polypropylene productproduced in the first stage) of 3-10 dl/g and

producing, in the third stage, a polypropylene product in such a mannerthat the intrinsic viscosity [η] of the entire product as a whole (thisintrinsic viscosity [η] refers to the intrinsic viscosity [η] of theentire polypropylene product containing the polypropylene productsproduced in the first and the second stages) of 0.8-6 dl/g.

In the above multistage polymerization, the first stage polymerizationmay preferably be performed under substantial absence of hydrogen. Forthe sequence of polymerization course, it is preferable to carry out theproduction of the polypropylene of relatively higher molecular weight inthe first stage and to effect thereafter production of the polypropyleneproduct(s) of relatively lower molecular weight in the subsequentstage(s). While the production sequence may be reversed, it should benecessary therefor to incorporate exhaustive elimination of themolecular weight regulator, such as hydrogen, included in the firststage reaction product before the initiation of polymerization in thesecond or subsequent stage(s), in order to produce a polypropyleneproduct of relatively lower molecular weight in the first stage and toproduce a polypropylene product of relatively higher molecular weight inthe second and the subsequent stages, so that employment of anintricated apparatus becomes necessary and attainment of increase in theintrinsic viscosity [η] of the polypropylene product in the second andthe subsequent stages may not be easy.

The polymerization in each stage may be realized either continuously orin a batchwise process. The polymerization may be performed in a knownpractice, for example, by slurry polymerization or by bulkpolymerization. The polymerization in the second and the subsequentstages may preferably be carried out subsequently to the first stagepolymerization in a continuous manner. When a batch process is employed,the multistage polymerization can be effected in one single reactor.

While it is favorable to carry out the polymerization of propylene ineach stage in a continuous manner in order to produce the firstpolypropylene resin composition according to the present invention in anefficient and economical way, a continuous polymerization may oftenbring about occurrence of gel formation. In order to suppress gelformation as scarce as possible, it is favorable to carry out theproduction of the polypropylene product of relatively lower molecularweight in the second and the subsequent stages using at leat twopolymerization reactors, preferably at least three reactors, in acontinuous manner in each reactor and to perform transference of thepolymerization product from a reactor to another reactor also in acontinuous way. By performing the production of polypropylene productscontinuously using a plurality of reactors, a polypropylene resincomposition exhibiting scarce occurrence of gel formation can beobtained.

For the catalyst for producing the highly stereospecific polypropyleneto be used in the production of the first and the second polypropyleneresin compositions according to the present invention, there may beemployed various known catalysts, for example, a catalyst composed of

(a) a solid catalyst component based on titanium, which has contents ofmagnesium, titanium, halogen and an electron donating agent,

(b) an organometallic compound catalyst component

(c) an organosilicic compound catalyst component having at least onesubstituent selected from the group consisting of cyclopentyl,cyclopentenyl, cyclopentadienyl and their derivatives.

The solid catalyst based on titanium (a) mentioned above can be preparedby bringing a magnesium compound (a-1), a titanium compound (a-2) and anelectron donor (a-3) into contact with each other.

As the magnesium compound (a-1), there may be enumerated magnesiumcompounds having reducing ability, such as compounds havingcarbon-to-magnesium bond or magnesium-to-hydrogen bond, and magnesiumcompounds having no reducing ability, such as those represented bymagnesium halogenides, alkoxymagnesium halides, aryloxymagnesiumhalides, alkoxymagnesiums, aryloxymagnesiums and carboxylic acid saltsof magnesium.

In preparing the titanium-based solid catalyst component (a), it ispreferable that, for example, a tetravalent titanium compoundrepresented by the formula (1) given below is employed as the titaniumcompound (a-2).

Ti(OR)_(g)X_(4−g)  (1)

In the formula (1), R represents a hydrocarbon group, X denotes ahalogen atom and g is in the range of 0≦g≦4.

Concrete examples of the above titanium compound represented by theformula (1) include titanium tetrahalides, such as TiCl₄, TiBr₄ andTiI₄; alkoxytitanium trihalides, such as Ti(OCH₃)Cl₃, Ti(OC₂H₅)Cl₃,Ti(O-n-C₄H₉)Cl₃, Ti(OC₂H₅)Br₃, and Ti(O-iso-C₄H₉)Br₃; dialkoxytitaniumdihalides, such as Ti(OCH₃)₂Cl₂, Ti(OC₂H₅)₂Cl₂, Ti(O-n-C₄H₉)₂Cl₂ andTi(OC₂H₅)₂Br₂; trialkoxytitanium monohalides, such as Ti(OCH₃)₃Cl,Ti(OC₂H₅)₃Cl, Ti(O-n-C₄H₉)₃Cl and Ti(OC₂H₅)₃Br; and tetraalkoxytitanium,such as Ti(OCH₃)₄, Ti(OC₂H₅)₄, Ti(O-n-C₄H₉)₄, Ti(O-iso-C₄H₉)₄ andTi(O-2-ethylhexyl)₄.

For the electron donor (a-3) to be incorporated in the preparation ofthe titanium-based solid catalyst component (a), there may beexemplified alcohols, phenols, ketones, aldehydes, esters of organic orinorganic acids, organic acid halides, ethers, acid amides, acidanhydrides, ammonia, amines, nitriles, isocyanates, nitrogen-containingcyclic compounds and oxygen-containing cyclic compounds.

In contacting the magnesium compound (a-1), the titanium compound (a-2)and the electron donor (a-3) with each other, it is permissible thatother reaction reagent, such as silicium, phosphorus or aluminum, may becaused to be present simultaneously and it is also permissible toincorporate a solid catalyst carrier for preparing a carrier-supportedsolid titanium catalyst component (a).

The titanium-based solid catalyst component (a) may be prepared by anytechnique including known one. Examples of such preparation techniqueare given below in a brief description:

(1) A technique in which a solution of the magnesium compound (a-1) in ahydrocarbon solvent containing the electron donor (the liquefying agent)(a-3) is brought into contact with the organometallic compound to causea reaction to presipitate solid matter which is then, or in the courseof precipitation, brought into contact with the titanium compound (a-2)to cause reaction.

(2) A technique in which a complex composed of the magnesium compound(a-1) and the electron donor (a-3) is brought into contact with theorganometallic compound to cause reaction and, then, the titaniumcompound (a-2) is caused to contact and react therewith.

(3) A technique in which the contacted product from the contact of aninorganic carrier with an organomagnesium compound (a-1) is brought intocontact with the titanium compound (a-2) and with the electron donor(a-3) to cause reaction therebetween. Here, it is permissible to bringthe product of contact of the carrier with the magnesium compound intocontact with a halogen-containing compound and/or an organometalliccompound preliminarily.

(4) A technique, wherein a solid carrier, which is obtained from amixture containing a solution of the magnesium compound (a-1), theelectron donor (a-3) and the carrier in a liquid medium of theliquefying agent and, optionally, a hydrocarbon solvent and on which themagnesium compound (a-1) is supported, is contacted with the titaniumcompound (a-2).

(5) A technique in which a solution containing the magnesium compound(a-1), the titanium compound (a-2), the electron donor (a-3) and,optionally, a hydrocarbon solvent is brought into contact with a solidcarrier.

(6) A technique in which an organomagnesium compound (a-1) in liquidform and a halogen-containing titanium compound (a-2) are brought intocontact with each other. In this case, the electron donor (a-3) is usedat least once.

(7) A technique in which an organomagnesium compound (a-1) in liquidform and a halogen-containing titanium compound (a-2) are brought intocontact with each other, whereupon the resulting product is caused tocontact with the titanium compound (a-2). In this case, the electrondonor (a-3) is used at least once.

(8) A technique in which an alkoxyl group-containing magnesium compound(a-1) is brought into contact with a halogen-containing titaniumcompound (a-2). In this case, the electron donor (a-3) is used at leastonce.

(9) A technique in which a complex composed of an alkoxylgroup-containing magnesium compound (a-1) and of the electron donor(a-3) is brought into contact with the titanium compound (a-2).

(10) A technique in which a complex composed of an alkoxylgroup-containing magnesium compound (a-1) and the electron donor (a-3)is brought into contact with an organometallic compound, whereupon theresulting product is brought into contact with the titanium compound(a-2).

(11) A technique in which the magnesium compound (a-1), the electrondonor (a-3) and the titanium compound (a-2) are brought into contactwith each other in a voluntary order to cause reactions therebetween. Itis permissible to incorporate a pretreatment of each reaction componentbefore these reactions using a reaction assistant, such as an electrondonor (a-3), an organometallic compound, a halogen-containing siliciumcompound or the like.

(12) A technique in which a liquid magnesium compound (a-1) exhibitingno reducing function is caused to react with a liquid titanium compound(a-2) in the presence of the electron donor (a-3) to deposit a solidmagnesium/titanium composite product.

(13) A technique in which the reaction product obtained in the above(12) is further reacted with the titanium compound (a-2).

(14) A technique in which the reaction product obtained in the above(11) or (12) is further reacted with the electron donor (a-3) and withthe titanium compound (a-2).

(15) A technique in which a solid mixture obtained by crushing themagnesium compound (a-1), the titanium compound (a-2) and the electrondonor (a-3) is treated with either an elementary halogen, a halogencompound or an aromatic hydrocarbon. In this case, it is permissible toincorporate a process step of crushing either the magnesium compound(a-1) solely, a complex composed of the magnesium compound (a-1) and ofthe electron donor (a-3) or the magnesium compound (a-1) and thetitanium compound (a-2). It is also permissible to subject the crushedproduct to a pretreatment with a reaction assistant, followed by anafter-treatment with, such as, an elementary halogen. As the reactionassistant, for example, an organometallic compound or ahalogen-containing silicium compound, may be employed.

(16) A technique in which the magnesium compound (a-1) is crushed andthe resulting crushed product is brought into contact with the titaniumcompound (a-2). Upon crushing and/or contacting the magnesium compound(a-1), an electron donor (a-3) may, if necessary, be employed togetherwith a reaction assistant.

(17) A technique in which the product obtained in either of the above(11)-(16) is treated with an elementary halogen or a halogen compound orwith an aromatic hydrocarbon.

(18) A technique in which a reaction product resulting after the metaloxide, the organomagnesium compound (a-1) and the halogen-containingcompound are contacted with each other is caused to contact with theelectron donor (a-3) and with, preferably, the titanium compound (a-2).

(19) A technique in which a magnesium compound (a-1), such as amagnesium salt of an organic acid, an alkoxymagnesium or anaryloxymagnesium, is brought into contact with the titanium compound(a-2), with the electron donor (a-3) and, if necessary, further with ahalogen-containing hydrocarbon.

(20) A technique in which a solution of the magnesium compound (a-1) andan alkoxytitanium in a hydrocarbon solvent is brought into contact withthe electron donor (a-3) and, if necessary, further with the titaniumcompound (a-2). In this case, it is favorable that a halogen-containingcompound, such as a halogen-containing silicium compound, is caused toco-exist.

(21) A technique in which a liquid magnesium compound (a-1) exhibitingno reducing function is caused to react with an organometallic compoundto cause a composite solid product of magnesium/metal (aluminum) todeposit out and, then, the product is reacted with the electron donor(a-3) and with the titanium compound (a-2).

As the organometallic compound catalyst component (b) mentioned above,those which contain a metal selected among the Group I to Group III ofthe periodic table are preferred. Concretely, there may be exemplifiedorganoaluminum compounds, complex alkyl compounds with Group I metal andaluminum, organometallic compounds of Group II metals and so on,represented by the formulae given below:

An organoaluminum compound (b-1) represented by the formula

R¹ _(m)Al(OR²)_(n)H_(p)X_(q)

In which R¹ and R² represent each a hydrocarbon group having usually1-15 carbon atoms, preferably 1-4 carbon atoms, which may be identicalwith or different from each other, X denotes a halogen atom, m is in therange 0<m≦3, n is in the range 0≦n<3, p is in the range 0≦p<3 and q isin the range 0≦q<3, wherein m+n+p+q=3.

An alkylated complex of a Group I metal and aluminum (b-2) representedby the formula

M¹AlR¹ ₄

In the formula, M¹ is Li, Na or K and R¹ has the same meaning as above.

A dialkylated compound of Group II or Group III metal (b-3) representedby the formula

R¹R²M²

In the formula, R¹ and R² have the same meanings as above and M² is Mg,Zn or Cd.

As the organoaluminum compound (b-1), there may be enumerated, forexample, those which are represented by the formula

R¹ _(m)Al(OR²)_(3−m),

in which R¹ and R² have the same meanings as above and m is preferablyof 1.5≦m≦3; those which are represented by the formula

R¹ _(m)AlX_((3−m)),

in which R¹ has the same meaning as above, X stands for a halogen and mis preferably of 0<m<3; those which are represented by the formula

R¹ _(m)AlH_((3−m)),

in which R¹ has the same meaning as above and m is preferably of 2≦m<3;and those which are represented by the formula

R¹ _(m)Al(OR²)_(n)X_(q),

in which R¹ and R² have the same meanings as above, X stands for ahalogen, m is in the range 0<m≦3, n is in the range 0≦n<3 and q is inthe range 0≦q<3, wherein m+n+q=3.

Concrete examples of the organosilicic compound catalyst component (c)include organosilicic compounds represented by the formula (2) givenbelow

SiR¹R² _(n)(OR³ )_((3−n))  (2)

In the formula (2), n is an integer of 0, 1 or 2, R¹ is a radicalselected from the group consisting of cyclopentyl, cyclopentenyl,cyclopentadienyl and their derivatives and R² and R³ denote each ahydrocarbyl radical.

As the concrete examples of R¹ in the formula (2), there may beenumerated cyclopentyl and derivatives thereof, such as cyclopentyl,2-methylcyclopentyl, 3-methylcyclopentyl, 2-ethylcyclopentyl,3-propylcyclopentyl, 3-isopropylcyclopentyl, 3-butylcyclopentyl,3-tert-butylcyclopentyl, 2,2-dimethylcyclopentyl,2,3-dimethylcyclopentyl, 2,5-dimethylcyclopentyl,2,2,5-trimethylcyclopentyl, 2,3,4,5-tetramethylcyclopentyl,2,2,5,5-tetramethylcyclopentyl, 1-cyclopentylpropyl and1-methyl-1-cyclopentylethyl; cyclopentenyl and derivatives thereof, suchas cyclopentenyl, 2-cyclopentenyl, 3-cyclopentenyl,2-methyl-1-cyclopentenyl, 2-methyl-3-cyclopentenyl,3-methyl-3-cyclopentenyl, 2-ethyl-3-cyclopentenyl,2,2-dimethyl-3-cyclopentenyl, 2,5-di-methyl-3-cyclopentenyl,2,3,4,5-tetramethyl-3-cyclopentenyl and2,2,5,5-tetramethyl-3-cyclopentenyl; cyclopentadienyl and derivativesthereof, such as 1,3-cyclopentadienyl, 2,4-cyclopentadienyl,1,4-cyclopentadienyl, 2-methyl-1,3-cyclopentadienyl,2-methyl-2,4-cyclopentadienyl, 3-methyl-2,4-cyclopentadienyl,2-ethyl-2,4-cyclopentadienyl, 2,2-dimethyl-2,4-cyclopentadienyl,2,3-dimethyl-2,4-cyclopentadienyl, 2,5-dimethyl-2,4-cyclopentadienyl and2,3,4,5-tetramethyl-2,4-cyclopentadienyl; derivatives of cyclopentyl, ofcyclopentenyl and of cyclopentadienyl, such as indenyl, 2-methylindenyl,2-ethylindenyl, 2-indenyl, 1-methyl-2-indenyl, 1,3-dimethyl-2-indenyl,indanyl, 2-methylindanyl, 2-indanyl, 1,3-dimethyl-2-indanyl,4,5,6,7-tetrahydroindenyl, 4,5,6,7-tetrahydro-2-indenyl,4,5,6,7-tetrahydro-1-methyl-2-indenyl,4,5,6,7-tetrahydro-1,3-dimethyl-2-indenyl and fluorenyl.

Concrete examples of the hydrocarbyl groups R² and R³ in the formula (2)include alkyls, cycloalkyls, aryls and aralkyls. If two or more groupsare present for R² or/and R³, the groups of R², or/and of R³ may eitherbe identical with or different from each other, wherein R² may either beidentical with or different from R³. The groups R¹ and R² in the formula(2) may be coupled with each other via a bridging group, such asalkylene.

Among the organosilicic compounds represented by the formula (2),preference is given to those in which R¹ stands for cyclopentyl, R²represents an alkyl or cyclopentyl and R³ stands for an alkyl,especially methyl or ethyl.

Concrete examples of the organosilicic compounds represented by theformula (2) include trialkoxysilanes, such ascyclopentyltrimethoxysilane, 2-methylcyclopentyltrimethoxysilane,2,3-dimethylcyclopentyltrimethoxysilane,2,5-dimethylcyclopentyltrimethoxysilane, cyclopentyltriethoxysilane,cyclopentenyltrimethoxysilane, 3-cyclopentenyltrimethoxysilane,2,4-cyclopentadienyltrimethoxysilane, indenyltrimethoxysilane, andfluorenyltrimethoxysilane; dialkoxysilanes, such asdicyclopentyldimethoxysilane, bis(2-methylcyclopentyl)dimethoxysilane,bis(3-tert-butylcyclopentyl)dimethoxysilane,bis(2,3-dimethylcyclopentyl)dimethoxysilane,bis(2,5-dimethylcyclopentyl)dimethoxysilane,dicyclopentyldiethoxysilane, dicyclopentenyldimethoxysilane,di(3-cyclopentenyl)dimethoxysilane,bis(2,5-dimethyl-3-cyclopentenyl)dimethoxysilane,di-2,4-cyclopentadienyldimethoxysilane,bis(2,5-dimethyl-2,4-cyclopentadienyl)dimethoxysilane,bis(1-methyl-1-cyclopentylethyl)dimethoxysilane,cyclopentylcyclopentenyldimethoxysilane,cyclopentylcyclopentadienyldimethoxysilane, diindenyldimethoxysilane,bis(1,3-dimethyl-2-indenyl)dimethoxysilane,cyclopentadienylindenyldimethoxysilane, difluorenyldimethoxysilane,cyclopentylfluorenyldimethoxysilane and indenylfluorenyldimethoxysilane;monoalkoxysilanes, such as tricyclopentylmethoxysilane,tricyclopentenylmethoxysilane, tricyclopentadienylmethoxysilane,tricyclopentylethoxysilane, dicyclopentylmethylmethoxysilane,dicyclopentylethylmethoxysilane, dicyclopentylmethylethoxysilane,cyclopentyldimethylmethoxysilane, cyclopentyldiethylmethoxysilane,cyclopentyldimethylethoxysilane,bis(2,5-dimethylcyclopentyl)cyclopentylmethoxysilane,dicyclopentylcyclopentenylmethoxysilane,dicyclopentylcyclopentadienylmethoxysilane anddiindenylcyclopentylmethoxysilane; and others, such asethylenebiscyclopentyldimethoxysilane.

For polymerizing propylene using a catalyst composed of the solidtitanium catalyst component (a), the organometallic compound catalystcomponent (b) and the organosilicic compound catalyst (c), aprepolymerization may be incorporated. In the prepolymerization, anolefin is polymerized in the presence of a solid titanium catalystcomponent (a), an organometallic compound catalyst component (b) and, ifnecessary, an organosilicic compound catalyst component (c).

For the olefin to be pre-polymerized, there may be used, for example, alinear olefin, such as ethylene, propylene, 1-butene, 1-octene,1-hexadecene or 1-eicosene; or an olefin having branched structure, suchas 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene,4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1- hexene,4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene,allylnaphthalene, allylnorbornane, styrene, dimethylstyrenes,vinylnaphthalenes, allyltoluenes, allylbenzene, vinylcyclohexane,vinylcyclopentane, vinylcycloheptane or allyltrialkylsilanes. They maybe co-polymerized.

The prepolymerization may favorably be carried out in such a manner thatthe polymerized product will be formed in an amount of about 0.1-1,000g, preferably 0.3-500 g per one gram of the solid titanium catalystcomponent (a). If the pre-polymerized amount is too large, theefficiency for producing the (co)polymer in the inherent polymerizationmay decrease. In the prepolymerization, the catalyst may be used at aconcentration considerably higher than that in the system of theinherent polymerization.

Upon the multistage polymerization of propylene using the catalyst asabove, it is permissible to subject propylene to a copolymerization withother comonomer(s) mentioned above in either one stage or in all thestages, so long as the purpose of the present invention is notobstructed.

In the multistage polymerization, propylene is subjected tohomo-polymerization or to copolymerization with other comonomer(s) ineach stage to produce a polypropylene product, wherein the polypropyleneproduct may preferably have a content of the structural unit ofpropylene exceeding 90 mole %, preferably in the range of 95-100 mole %.The content of the structural unit of propylene in each stage can beadjusted by, for example, altering the amount of hydrogen supplied toeach polymerization system. However, it is preferable to effect thepolymerization in the first stage without supplying hydrogen thereto,when a high molecular weight polypropylene is to be produced there.

On the multistage polymerization of propylene, it is permissible toincorporate in the polymerization process a stage of copolymerization ofpropylene with ethylene in addition to the prulality of polymerizationstages mentioned above, in order to form a propylene/ethylene copolymerrubber to produce a propylene block-copolymer.

For the intrinsic polymerization, it is favorable to use the solidtitanium catalyst component (a) (or the catalyst for theprepolymerization) in an amount of about 0.0001-50 mmol, preferablyabout 0.001-10 mmol, calculated as titanium atom, per one liter of thepolymerization volume. The organometallic compound catalyst component(b) may favorably be used in an amount of about 1-2,000 moles,preferably about 2-500 moles, as calculated for the atomic weight of themetal per one mole of titanium atom in the polymerization system. Theorganosilicic compound catalyst component (c) may favorably be used inan amount of about 0.001-50 moles, preferably about 0.01-20 moles, perone mole of the metal atom of the organometallic compound catalystcomponent (b).

The polymerization may be effected in either of gas phase polymerizationor liquid phase polymerization such as solution polymerization andsuspension polymerization, wherein each stage may be realized in adifferent way. It may be performed either in a batchwise, continuous orsemi-continuous way. Each of the stages may be performed in a pluralityof polymerization reactors, for example, in 2-10 reactors. Forindustrial production, it is most preferably to carry out thepolymerization in continuous way, wherein preference is given to such apractice that the polymerization in the second or the subsequent stageis effected in at least two separate polymerization reactors, wherebygel-formation can be suppressed.

As the polymerization medium, inert hydrocarbon may be used andpropylene in liquid state may be used therefor. The polymerizationcondition may be selected adequately within the ranges for thepolymerization temperature of about −50° C. to +200° C., preferablyabout 20° C. to 100° C., and for the polymerization pressure of normalpressure to 9.8 MPa (normal pressure to 100 kgf/cm² gauge), preferablyabout 0.2 to 4.9 MPa (about 2 to 50 kgf/cm² gauge).

The first polypropylene resin composition and the second polypropyleneresin composition according to the present invention can be used afterblending them. It is permissible that each of the first and the secondpolypropylene resin compositions according to the present inventioncontains on requirement other polymer(s) and/or additives etc., so longas the purpose of the present invention is not obstructed. As the saidother polymers, polypropylenes which are not included in the first andthe second polypropylene resin compositions according to the presentinvention, for example, homopolymer of propylene and propylene/α-olefincopolymers, are enumerated. As others, there may be enumerated, forexample, low density polyethylene (LDPE), linear low densitypolyethylene (LLDPE), high density polyethylene (HDPE), polyolefins,rubber components and engineering plastics. For example, the first orthe second polypropylene resin composition according to the presentinvention may contain, for improving the impact strength, a rubbercomponent, such as an ethylene/α-olefin copolymer rubber or a rubberbased on a conjugated diene, in an adequate amount. Concrete examples ofsuch a rubber component include non-crystalline or low-crystallineα-olefin copolymers having no diene component, such asethylene/propylene copolymer rubber, ethylene/1-butene copolymer rubber,ethylene/1-octene copolymer rubber and propylene/ethylene copolymerrubber; ethylene/propylene/dicyclopentadiene copolymer rubber;ethylene/propylene/non-conjugated diene copolymer rubber, such asethylene/propylene/1,4-hexadiene copolymer rubber,ethylene/propylene/cyclooctadiene copolymer rubber,ethylene/propylene/methylenenorbornene copolymer rubber andethylene/propylene/ethylidenenorbornene copolymer rubber; andethylene/butadiene copolymer rubber.

As the additives, there may be enumerated, for example, nucleatingagent, antioxidant, hydrochloric acid absorber, heat stabilizer,anti-weathering agent, light stabilizer, UV-absorber, slipping agent,anti-blocking agent, antifogging agent, lubricating agent, antistaticagent, flame retardant, pigments, colorants, dispersant,copper-sequestering agent, neutralizing agent, foaming agent,plasticizer, bubble preventing agent, cross-linking agent, flowabilityimproving agent such as peroxides, weld strength improving agent,natural petroleum oils, synthetic oils, waxes and inorganic fillers suchas talc etc.

The first and the second polypropylene resin compositions according tothe present invention may contain the above-mentioned prepolymer, as anucleating agent, or an inherent nucleating agent chosen among knownones or, further, the above-mentioned prepolymer together with aninherent nucleating agent. By inclusion or addition of a nucleatingagent, micronization of the crystal grains and increment of thecrystallization velocity are attained, whereby a high speed molding canbe realized. For example, when a nucleating agent is contained in thefirst and the second polypropylene resin compositions according to thepresent invention, it is possible to provide for a micronization of thecrystals together with attainment of increased crystallization velocityto permit high speed molding. For the nucleating agent other than theprepolymer mentioned above, various nucleating agent known previously,such as nucleating agents based on phosphate, sorbitol, metal salts ofaromatic or aliphatic carboxylic acids and inorganic substances, may beemployed without any restriction.

The first and the second polypropylene resin compositions according tothe present invention have a high melt tension (MT) and are superior inthe moldability and in the stiffness, so that they can be processed intomolded articles of not only small sizes but also large sizes, which havebetter appearance and are difficultly deformable. Therefore, the firstand the second polypropylene resin compositions according to the presentinvention can be used without any limitation for various applicationfields where the above-mentioned characteristic properties are required.Thus, they are adapted for use as the starting material of, for example,blow-molded articles, vacuum-formed articles, pressure-formed articles,calendered articles, stretched films, inflation films, extrusion moldedarticles and foamed articles, while they can be used as the startingmaterial for other molded articles and for other molding techniques.

The resin composition for blow molding according to the presentinvention is constituted of a resin blend comprising the first and/orthe second polypropylene resin composition, other resins including oneor more ethylenic polymers including a low density polyethylene (LDPE)and a high density polyethylene (HDPE), an ethylene/α-olefin randomcopolymer and elastomer(s) based on styrene, fillers and additives. Theproportion of the summed-up amount of the first and the secondpolypropylene resin compositions according to the present invention inthe resin composition for blow molding may favorably be in the range of50-99% by weight, preferably 50-90% by weight. The resin composition forblow molding according to the present invention per se has also a highmelt tension (MT) and is superior in the moldability and in thestiffness, so that it can be used favorably as the material to beprocessed by blow molding, in particular for large-sized articles, suchas for example, those in which the weight of the parison is 5 kg orhigher.

The blow-molded article according to the present invention is a hollowproduct prepared by subjecting the first or the second polypropyleneresin composition according to the present invention, or the resincomposition for blow molding according to the present invention, to ablow molding. For blow molding the first polypropylene resin compositionaccording to the present invention, it is preferable that the firstpolypropylene resin composition has the following characteristic feature8), namely,

8) that the relationship between the melt tension (MT), determined byFlow Tester at 230° C., and the critical shearing rate (SRc) meets thefollowing formula (I), preferably the following formula (I′):

MT>−4.16×Ln(SRc)+29  (I)

MT>−4.16×Ln(SRc)+33  (I′)

in which MT represents the melt tension in gram. SRc represents thecritical shearing rate in sec⁻¹ and Ln indicates the natural logarithm.

The blow-molded article according to the present invention is producedfrom the polypropylene resin composition according to the presentinvention having a high melt tension, so that the parison will scarcelysuffer from occurrence of draw-down and from occurrence of waving andrough surface even in a large-sized parison. Therefore, blow-moldedarticles of not only small size but also large size can be obtainedeasily with better appearance in an efficient manner. For example, alarge-sized blow-molded article, such as bumper or spoiler of automobileproduced from a parison having a weight of 5 kg or more, can be producedat a high speed efficiently. Due to the superior stiffness, theresulting blow-molded articles are scarcely deformable.

For producing the blow-molded article according to the present inventionfrom the above-mentioned polypropylene resin composition, known blowmolding apparatuses can be employed. The molding conditions may also bethose known ones.

In the case of extrusion blow molding, a blow-molded article can beobtained by extruding the polypropylene resin composition according tothe present invention in a molten state at a resin temperature of, forexample, 170 to 300° C., preferably 170 to 270° C., through a die toform a tubular parison and placing this parison in a mold having theshape corresponding to that of the molded article, whereupon air isblown into this parison at a resin temperature of 130 to 300° C.,preferably 200 to 270° C., in order to fit it to the mold inner face toobtain the contemplated blow-molded article. The extension magnificationmay preferably be 1.5- to 5-fold in the lateral direction.

In the case of injection blow molding, the polypropylene resincomposition according to the present invention is injected into a moldat a resin temperature of, for example, 170 to 300° C., preferably 170to 270° C., to form a parison, whereupon the parison is placed in a moldof a shape corresponding to that of the molded article and air is blowninto the parison in order to fit it to the mold at a resin temperatureof 120 to 300° C., preferably 140 to 270° C., to obtain the blow-moldedarticle. The extension magnification may preferably be 1.1- to 1.8-foldin the longitudinal direction and 1.3- to 2.5-fold in the lateraldirection.

In the case of stretching blow molding, the polypropylene resincomposition according to the present invention is injected into a moldat a resin temperature of, for example, 170 to 300° C., preferably 170to 280° C., to form a parison which is then preliminarily blown under apredetermined condition, whereupon this pre-blown parison is subjectedto a stretching blow molding at a resin temperature of 80 to 200° C.,preferably 100 to 180° C., to obtain the blow-molded article. Theextension magnification may preferably be 1.2- to 4.5-fold in thelongitudinal direction and 1.2- to 8-fold in the lateral direction.

Concrete examples of the blow-molded article according to the presentinvention include automobile exterior furnishings, such as spoiler,bumper, side molding, front grill guard and bumper guard; automobileinterior furnishings, such as sun visor, radiator tank, washer tank,ducts, distributor, evaporator casing, console box, indicator panel anddoor trim; vessels, such as kerosene tank, vessels for foods, shampoocartridge, containers for cosmetics, containers for detergents, vesselsfor drugs and containers for toner; and others, such as toys andcontainers. Among them, large-sized blow-molded articles with parisonweights of 5 kg and higher, in particular, automobile exteriorfurnishings, such as bumper and spoiler, may favorably be enumerated.

The vacuum- or pressure-formed article according to the presentinvention is produced by processing a sheet or film made of the first orthe second polypropylene resin composition according to the presentinvention by vacuum- or pressure forming. Due to the high melt tensionof the starting polypropylene resin composition, the sheet or film cansufficiently fit the shape of the mold inner face upon the vacuum- orpressure forming. Therefore, it can be processed by vacuum- or pressureforming at higher speed even in a large-sized article and permits deepdrawing while providing superior strength and better appearance.

For producing the vacuum- or pressure-formed article according to thepresent invention from the polypropylene resin composition according tothe present invention, known apparatuses for vacuum-forming or forpressure forming can be used. The forming conditions may also be thoseknown ones. Thus, for example, a formed article in a form of sheet madeof the polypropylene resin composition according to the presentinvention is held on a mold having a shape corresponding to that to beassumed at a temperature of 180-300° C., preferably 180-270° C., morepreferably 180-250° C., and, then, by evacuating the mold or byintroducing a compressed air into the mold cavity, contemplated vacuum-or pressure-formed article can be obtained.

Concrete examples of the vacuum- or pressure-formed article according tothe present invention include automobile interior furnishings, such asroof liner, refrigerator interior articles, laundry machine interior andexterior parts, jerry packages, instant lunch package, trays, trays forfoods, foamed trays for foods, package for bean curd, cups, bags, heatresistant trays for electronic oven, protecting cases for machines andpackaging cases for merchandizes.

The calendered article according to the present invention is produced bycalendering the first or the second polypropylene resin compositionaccording to the present invention. Due to the high melt tension of thestarting polypropylene resin composition according to the presentinvention, sheet or film superior in the strength and gloss exhibitingscarce irregularity of thickness can easily be calendered at high speed.

For producing the calendered article according to the present inventionfrom the polypropylene resin composition, known calendering apparatusescan be employed. The calendering conditions may also be known ones. Forexample, using a calendering machine of, for example, the series type,L-shaped type, reverse L-shaped type or Z-shaped type, calendering canbe effected at a resin temperature of 180-300° C., preferably 180-270°C., and at a heating roll temperature of 170-300° C., preferably170-270° C. It is also possible to produce an artificial leather,waterproof cloth or various laminates by feeding paper or cloth to theroll upon calendering.

Concrete examples of the calendered article according to the presentinvention include original sheets for processing into various cards andoriginal sheets for producing household commodities.

The extrusion molded article according to the present invention isproduced by extrusion-molding the first or the second polypropyleneresin composition according to the present invention. Due to the highmelt tension of the starting polypropylene resin composition accordingto the present invention, it can be subjected to extrusion molding athigh speed and can be processed into a large-sized article having a highstrength. In the case where the extrusion-molded article according tothe present invention is an extruded sheet, the thickness thereof mayrange usually from 0.3 to 5 mm, preferably from 0.5 to 3 mm.

For producing the extrusion-molded article according to the presentinvention from the polypropylene resin composition according to thepresent invention, known extrusion apparatuses can be employed. Forexample, an extruding machine, such as monoaxial screw extruder, kneaderextruder, ram extruder or gear extruder, can be used to produce anextruded sheet. The extruder may be provided with a circular die or aT-die. The conditions of extrusion may also be known ones, while it ispreferable to effect the extrusion under the condition such as givenbelow. For example, using an extruder provided with a T-die, a sheet maypreferably be extruded at a resin temperature of 180-300° C., preferably180-270° C., and at a T-die temperature of 180-300° C., preferably180-290° C. For cooling the extruded article, water can be used, whileother means, such as air-knife or cooling roll, may also be employed. Itis also possible to produce an artificial leather, waterproof cloth orvarious laminates by feeding paper or cloth to the roll upon theextrusion.

Concrete examples of the extrusion-molded article according to thepresent invention include architectural furnishings, such as eavesgutter, curtain rail, window frame, shelves and door; extruded profilearticles, such as cable ducts, roller shutters and shutters; and others,such as tubes, pipes, electric cables (sheathed), films, sheets, boards,fiber and tape.

The stretched film according to the present invention is a monoaxiallyor biaxially stretched film produced by stretching a sheet or film madeof the first or the second polypropylene resin composition according tothe present invention. Due to the high melt tension of the startingpolypropylene resin composition according to the present invention, theresulting stretched film is superior in the thickness accuracy and canbe produced at high speed stably without suffering from breaking of thefilm during the stretching. The stretched film according to the presentinvention has a thickness of, usually, 5-200 μm, preferably 10-120 μm.The stretching magnification ratio of the stretched film according tothe present invention for biaxially stretched film is in the range of,usually, 9- to 100-fold, preferably 40- to 70-fold, and that formonoaxially stretched film in the range of, usually, 2- to 10-fold,preferable 2- to 6-fold.

For producing the stretched film according to the present invention fromthe polypropylene resin composition according to the present invention,known stretching apparatuses can be employed. For example, a tenter(with axial/lateral stretching or lateral/axial stretching), asimultaneous biaxial stretching machine or a monoaxial stretchingmachine may be exemplified. The conditions of stretching may also beknown ones. For example, by melt-extruding the polypropylene resincomposition according to the present invention at a temperature of200-280° C., preferably 240-270° C., and stretching the resulting filmup to 2- to 10-fold, preferably 2- to 6-fold in axial direction, amonoaxially stretched film can be produced. In an alternative technique,a biaxially stretched film can be obtained by melt-extruding thepolypropylene resin composition according to the present invention at atemperature of 200-280° C., preferably 240-270° C., and stretching theresulting film under an atmosphere of 120-200° C., preferably 130-180°C., up to 3- to 10-fold in axial direction and up to 3- to 10-fold inlateral direction.

Concrete examples of the stretched film according to the presentinvention include packaging films for foods, such as candy andvegetable; shrinkable films for wrapping cup-noodle etc.; packaging filmfor packaging textile goods, such as utility shirt, T-shirt and pantystocking; films for office supplies, such as clear file, clear sheet;and others, such as capacitor film, cigarette packaging film, film forinstant packaging, decoration film and packaging tape.

The inflation film according to the present invention is produced bysubjecting the first or the second polypropylene resin compositionaccording to the present invention to an inflation molding. Due to thehigh melt tension of the starting polypropylene resin compositionaccording to the present invention, the balloon formed upon theinflation molding is held stable. Therefore, the inflation filmaccording to the present invention exhibits scarce decrease in thestrength and in the transparency and is superior in the stiffness and inthe transparency, while permitting a high-speed molding, as seen in thefilm made of a resin blended with a high-pressure low densitypolyethylene.

For producing the inflation film according to the present invention fromthe polypropylene resin composition, known inflation-molding apparatusescan be employed. The conditions for the molding may also be those knownones. For example, a condition of a resin temperature of 180-240° C., anair cooling in one or two stages at an air temperature of 10-40° C., arolling-up velocity of 5-200 m/min. and an inflation ratio of 1.1- to5-fold may be employed. The inflation film may have a thickness in therange of 10 μm to 1 mm, preferably 15 μm to 0.5 mm.

Concrete examples of the inflation film according to the presentinvention include packaging films for foods, such as candy andvegetable; packaging film for packaging textile goods, such as utilityshirt, T-shirt and panty stocking; films for office supplies, such asclear file, clear sheet; and others, such as cleaning bag, films forfashion bags, films for agricultural uses and cup.

The foamed article according to the present invention is produced bycausing the first or the second popypropylene resin compositionaccording to the present invention to foam up. To the technique foreffecting the foaming, no special limitation is imposed and knowntechniques, such as foaming under normal pressure, extrusion foaming,pressure foaming, injection foaming and beads forming, can be employed.Due to the high melt tension of the starting polypropylene resincomposition according to the present invention, foaming can be effectedat a high foaming-up ratio in a uniform cell texture even for alarge-sized foamed article. The foamed article according to the presentinvention can be produced by heating a foamable composite composed ofthe polypropylene resin composition according to the present invention,foaming agent (propellant) and, on requirement, foaming nucleatingagent, organic peroxide, cross linking assistant and so on.

As the foaming agent, chemicals which exist as liquid or solid at normaltemperature and develop a gas by heating can be used. Concretely, theremay be employed, for example, azodicarbonamide, barium azodicarboxylate,N,N′-dinitrosopentamethylenetetramine,4,4-oxybis(benzenesulfonylhydrazide),diphenylsulfon-3,3-disulfonylhydrazide, p-toluenesulfonyl semicarbazide,trihydrazinotriazine, biurea and zinc carbonate. Among them, preferenceis given to compounds which develop a large amount of gas and has a gasdevelopment cease temperature sufficiently lower than the startingtemperature of thermal deterioration of the polypropylene resincomposition, for example, azodicarbonamide,N,N′-dinitrosopentamethylenetetramine and trihydrazinotriazine. Thesefoaming agents may preferably be present in the polypropylene resincomposition in a proportion of, favorably, 1-20 parts by weight,preferably 2-5 parts by weight, per 100 parts by weight of thepolypropylene resin composition.

Foaming agents other than the above may also be employed, for example,gases existing in gas phase at normal temperature and normal pressure,such as carbon dioxide, nitrogen, argon, helium, propane, butane,chlorofluorocarbons (flons), methane, ethane, oxygen and air; lowboiling volatile foaming agents (low boiling organic solvents), such asn-pentane, iso-pentane, n-hexane, n-heptane, n-octane, cyclopentane,cyclohexane, methanol, ethanol, 1-butanole, 3-pentanol, acetone, methylethyl ketone and diethyl ether. Among them, preference is given tocarbon dioxide and nitrogen.

The nucleating agent for the foaming is used to control the diameter andnumber of gas bubbles of the foamed article. Concrete examples of thefoaming nucleating agent include talc, sodium bicarbonate, citric acid,calcium carbonate and ammonium carbonate.

The organic peroxide mentioned above is used for attaining cross-linkingof the foamed product. As the organic peroxide, there may be employed inmost cases organic peroxides and organic peroxyesters. Concrete examplestherefor include the following compounds:

3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, decanoyl peroxide,lauroyl peroxide, succinic acid peroxide, acetyl peroxide, tert-butylperoxy(2-ethyl hexanoate), m-toluoyl peroxide, benzoyl peroxide,tert-butyl peroxyisobutyrate,1,1-bis(tert-butylperoxy)-3,5,5-trimethylcyclohexane,1,1-bis(tert-butylperoxy)cyclohexane, tert-butyl peroxymaleate,tert-butylperoxylaurate, tert-butylperoxy-3,5,5-trimethylcyclohexanoate,cyclohexanone peroxide, tert-butylperoxyisopropyl carbonate,2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butylperoxyacetate,2,2-bis(tert-butylperoxy)butane, tert-butylperoxybenzoate,n-butyl-4,4-bis(tert-butylperoxy)valerate,di-tert-butylperoxyisophthalate, methyl ethyl ketone peroxide,α,α′-bis(tert-butylperoxyisopropyl)benzene, dicumyl peroxide,2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylcumyl peroxide,diisopropylbenzene hydroperoxide, di-tert-butyl peroxide, p-menthanehydroperoxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne,1,1,3,3-tetramethylbutyl hydroperoxide,2,5-dimethylhexane-2,5-dihydroperoxide, cumene hydroperoxide andtert-butyl-hydroxy peroxide.

Among them, preference is given to 1,1-bis(tert-butylperoxy)cyclohexane,tert-butylperoxy maleate, tert-butylperoxy laurate,tert-butylperoxy-3,5,5-trimethyl cyclohexanoate, cyclohexanone peroxide,tert-butylperoxyisopropyl carbonate,2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butylperoxy acetate,2,2-bis(tert-butylperoxy)butane, tert-butylperoxy benzoate,n-butyl-4,4-bis(tert-butylperoxy) valerate, di-tert-butylperoxyisophthalate, methyl ethyl ketone peroxide,α,α′-bis(tert-butylperoxyisopropyl)benzene, dicumyl peroxide,2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylcumyl peroxide,diisopropylbenzene hydroperoxide, di-tert-butyl peroxide, p-menthanehydroperoxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne,1,1,3,3-tetramethylbutyl hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, cumene hydroperoxide and tert-butylhydroxy peroxide. Theorganic peroxide may favorably be used in an amount of 0.01-5 parts byweight, preferably 0.01-1 part by weight, per 100 parts by weight of thepolypropylene resin composition.

The cross linking assistant functions such that a hydrogen atom in thepolypropylene is drawn out by the organic peroxide and the therebyproduced polymer radical will react with the cross linking assistantbefore it comes to cleavage to thereby stabilize the polymer radicaland, at the same time, to increase the cross linking efficiency. As thecross linking assistant functioning as above, there may be used usuallyunsaturated compounds having one or two or more double bonds, oximes,nitroso compounds and maleimides each solely or in a combination of twoor more of them.

As the crosslinking assistant, there may be enumerated concretely, forexample, divinyl compounds, such as divinylbenzene and diallylphthalate; polyfunctional methacrylates and acrylates, such as1,6-hexanediol dimethacrylate, ethyleneglycol dimethacrylate,trimethylolpropane trimethacrylate, pentaerythritol triacrylate andneopentylglycol diacrylate; cyanurates and isocyanurates, such astriallyl cyanurate and triallyl isocyanurate; oximes, such as quinonedioxime and benzoquinone dioxime; nitroso compounds, such asp-nitrosophenol and the like; and maleimides, such asN,N-methaphenylenebismaleimide and so on. Among them, preferance isgiven to 1,6-hexanediol dimethacrylate and neopentylglycol diacrylate.

The foamed article according to the present invention may have anyshape. It may be present in a form of, for example, block, sheet andmonofilament. For producing the foamed article according to the presentinvention using the polypropylene resin composition according to thepresent invention, known foam-molding apparatus can be used. The moldingconditions may also be known ones.

For example, a foamed article in a form of sheet can be obtained byblending the polypropylene resin composition according to the presentinvention, a foaming agent which is present in liquid or solid state atnormal temperature and which develops a gas by heating, an organicperoxide, a cross linking assistant and, if necessary, a heat stabilizeron a mixing apparatus, such as Henschel mixer, V-blender, ribbon blenderor tumbler blender, kneading the resulting blend using an extruder,preferably that provided with a gas bent, while heating it at atemperature at which the organic peroxide will be decomposed but not thefoaming agent and while removing the unnecessary volatile substances viathe bent which is disposed at a portion downstream the high temperatureheating zone and extruding the molten blend through a T-die or acircular die arranged on the extruder to thereby obtain a foamable sheetwhich contains the foaming agent in substantially undecomposed state andwhich has been subjected to cross linking. This foamable sheet is thenbrought into foaming by a known foaming technique, for example, pressfoaming in which the foaming agent is decomposed under a pressurizedcondition, a heat foaming in a molten salt bath in which the foamingagent is decomposed by heating under normal pressure, heat foaming in ahot blast oven, heat foaming by thermal radiant ray, heat foaming bymicrowave or combination of these techniques, to obtain a foamedarticle.

In an alternative method for producing a foamed article, a substantiallyfoamed sheet can be obtained by blending the polypropylene resincomposition according to the present invention, a foaming agent which ispresent in liquid or solid state at normal temperature and whichdevelops a gas by heating and, if necessary, a heat stabilizer and soon, on a mixing apparatus, such as Henschel mixer, V-blender, ribbonblender or a tumbler blender, kneading the resulting blend using anextruder, while heating it at a temperature at which the foaming agentwill be decomposed, and extruding the molten blend through a T-die or acircular die arranged on the extruder.

In a further alternative method for producing a foamed article, a foamedsheet can be produced by blending the polypropylene resin compositionaccording to the present invention, a foaming nucleating agent and, ifnecessary, a heat stabilizer and so on, on a mixing apparatus, such asHenschel mixer, V-blender, ribbon blender or a tumbler blender, kneadingthe resulting blend using an extruder, while supplying continuouslythereto a gas which is present at normal temperature and normal pressurein gas phase or a low boiling volatile foaming agent (low boilingorganic solvent) via a nucleating agent feed nozzle disposed midway inthe extruder cylinder and extruding the kneaded mass through a T-die ora circular die arranged on the extruder into a substantially foamedsheet.

By the method for producing the foamed article using a gas which existsin gas phase at normal temperature and normal pressure or a low boilingvolatile foaming agent as described above, a foamed sheet having a finefoam cell structure of high foaming magnification ratio of, for example,at least 2-fold, with an average foam cell diameter of about 100 μm canbe obtained. When a conventional polypropylene resin or a polypropyleneresin composition other than the polypropylene resin compositionaccording to the present invention is used as the starting resin, it isdifficult to obtain a foamed sheet of a high foaming magnificationratio. Thus, for example, it is difficult to obtain a foamed sheethaving a foaming magnification ratio of at least 2-fold and a fine foamcell structure with an average foam cell diameter of about 100 μm.

In a further alternative method for producing a foamed article, thepolypropylene resin composition according to the present invention and,on requirement, heat stabilizer and so on are kneaded on a mixingapparatus, such as Henschel mixer, V-blender, ribbon blender or atumbler blender, and the resulting blend is kneaded using an extruder toobtain a pelletized product. This pelletized product and a low boilingvolatile foaming agent (low boiling organic solvent) are treated in ahigh-pressure vessel at a high temperature to obtain impregnated beads.The resulting impregnated beads are heated by hot steam to cause apreliminary foaming in order to adjust the diameter of the prefoamedcell, whereupon the so treated beads are transferred to a ripeningprocess step for restoring the internal pressure of the beads to normalpressure and are contacted with air sufficiently. The resulting ripenedbeads are then heated in a mold by, for example, hot steam, to causefinal foaming to obtain foamed article.

Concrete examples of the foamed article according to the presentinvention include office supplies, such as file cases; automobileinertia furnishings, such as roof liner and so on; and others, such astrays, trays for food products, cups for noodles, lunch boxes,containers for fast foods, containers for retorts, vessels for frozenfoods, vessels for cooked foods, heat resistant vessels for electronicoven, cups, synthetic timber, original rolled product of various foamedsheets, shock absorbers, heat insulators, sound insulators and vibrationdamping material.

For molding formed articles, such as blow-molded articles, vacuum- orpressure formings, calendered articles, extrusion-molded articles,stretched films, inflation films and various foamed articles using thefirst or the second polypropylene resin composition according to thepresent invention, the starting polypropylene resin composition mayfavorably contain at least one stabilizer among phenolic stabilizer,organophosphite stabilizer, thioether stabilizer, hindered aminestabilizer and higher fatty acid metal salts. Such additives mayfavorably be used each in an amount of 0.005-5 parts by weight,preferably 0.01-0.5 part by weight per 100 parts by weight of thepolypropylene resin composition according to the present invention.

As described above, the first polypropylene resin composition accordingto the present invention has, due to the material properties specified,a high melt tension and are superior in the moldability and can affordto process into formed articles which have better appearance and highstiffness and which are scarcely subject to deformation, even forlarge-sized articles, efficiently at high speed.

The second polypropylene resin composition according to the presentinvention has, due to the material properties specified, a high melttension and are superior in the moldability and can afford to processinto formed articles which have better appearance and high stiffness andwhich are scarcely subject to deformation, even for large-sizedarticles, efficiently at high speed.

By the process for producing the polypropylene resin compositionaccording to the present invention, the polypropylene resin compositiondescribed above can be produced in a simple and efficient manner at alow cost, based on the fact that, in the first polymerization stage, ahigh molecular weight polypropylene product having an intrinsicviscosity [η] of 8-13 dl/g is produced up to a definite yield and, inthe second and subsequent polymerization stages, polymerization ofpropylene is effected in such a way that a polypropylene product havingan intrinsic viscosity [η] of lower than 8 dl/g is produced and the meltflow rate (MFR) of the finally obtained polypropylene resin compositionas a whole will be in the range of 0.01-5 g/10 min.

The resin composition for blow molding according to the presentinvention can afford to process into blow-molded articles which have abetter appearance and are scarcely subject to deformation even forlarge-sized articles, in an efficient manner at high speed, since itcontains the first or the second polypropylene resin compositiondescribed above.

The blow-molded article according to the present invention is obtainedby blow-molding the above-mentioned resin composition and, therefore,the parison will scarcely suffer from occurrence of draw-down, so thatthe blow-molded article is obtained efficiently at high speed and, inaddition, is better in the appearance and difficultly deformable.

The vacuum- or pressure-formed article according to the presentinvention is produced by a vacuum- or pressure forming of thepolypropylene resin composition described above, so that it may bepermitted to be produced as a large-sized article in a high-speedproduction and to be processed by deep drawing and, in addition, it issuperior in the stiffness and in the appearance.

The calendered article according to the present invention is produced bysubjecting the polypropylene resin composition described above to acalendering, so that it may be permitted to be produced as a large-sizedarticle and by high speed calendering and, in addition, it has scarcethickness irregularity and is superior in the gloss, in the appearanceand in the stiffness.

The extruded article according to the present invention is produced bysubjecting the polypropylene resin composition described above to anextrusion molding, so that it may be permitted to be produced as alarge-sized article and in a high speed molding and, in addition, it issuperior in the appearance and in the stiffness.

The stretched film according to the present invention is produced bysubjecting a sheet or film made of the polypropylene resin compositiondescribed above to stretching, so that it may be permitted to beproduced as a large-sized article and in a high speed stretching and, inaddition, it can be obtained by a stable stretching without sufferingfrom breaking of the film during the stretching and is also superior inthe thickness accuracy.

The inflation film according to the present invention is produced bysubjecting the polypropylene resin composition described above to aninflation molding, so that it may be permitted to be produced as alarge-sized article and by a high speed molding and, in addition, it isobtained from a baloon held in a stable state and, therefore, issuperior in the appearance and also in the stiffness and transparency.

Due to the fact that the foamed article according to the presentinvention is produced by subjecting the polypropylene resin compositiondescribed above to foaming, it may be permitted to be produced as alarge-sized article and by a high speed molding and, in addition, it maybe present as a foamed article having a fine and uniform foam cellstructure of high foaming magnification ratio.

THE BEST MODE FOR EMBODYING THE INVENTION

Below, the present invention will be described by way of Examples.

<<Preparation of the Solid Titanium Catalyst Component>>

Production Example 1 -1) Solid Titanium Catalyst Component-1

A vibration mill was employed which is equipped with four crusher potseach having an inner volume of 4 liters and containing therein 9 kg ofsteel balls of 12 mm diameter. Each pot was charged with 300 g ofanhydrous magnesium chloride, 115 ml of diisobutyl phthalate and 60 mlof titanium tetrachloride under a nitrogen atmosphere and the contentswere crushed for 40 hours. 5 grams of the resulting co-crushed mass wereplaced in a 200 ml flask, whereto 100 ml of toluene were added and themixture was agitated at 114° C. for 30 minutes, whereupon the mixturewas stood still and the supernatant was removed. Then, the residue waswashed with each 100 ml of n-heptane at 20 ° C. Washing was repeatedthree times. Then, the washed solids were dispersed in 100 ml ofn-heptane to obtain a slurry of solid titanium catalyst component-1. Theresulting solid titanium catalyst component-1 contained 2.0% by weightof titanium and 18% by weight of diisobutyl phthalate.

Production Example 2 -2) Solid Titanium Catalyst Component-2

4.8 kg of anhydrous magnesium chloride, 25.0 liters of decane and 23.4liters of 2-ethylhexyl alcohol were charged in a 200 liter autoclave andwere heated and reacted at 130° C. for 2 hours to convert them to ahomogeneous solution. To this solution were then added 11.1 kg ofphthalic anhydride and the mixture was agitated at 130° C. for furtherone hour to dissolve the phthalic anhydride so as to obtain ahomogeneous solution. The resulting homogeneous solution was cooled downto room temperature, whereupon all of this homogeneous solution wasadded dropwise to 200 liters of titanium tetrachloride maintained at−20° C. over a period of one hour. After the addition was over, thetemperature of the resulting mixed liquid was elevated to 110° C. over aperiod of 4 hours. On reaching the temperature of 110° C., 2.7 liters ofdiisobutyl phthalate were added thereto and the mixture was agitated forsubsequent two hours while maintaining this temperature. After this 2hours' reaction, the mixture was hot filtrated to collect the solidmatter, which was washed with hexane at 110° C. The washing was effecteduntil the concentration of free titanium compound in the washed liquorwill be 0.1 mmol/l or lower. By the procedures as above, solid titaniumcatalyst component-2 was obtained.

Production Example 3

An autoclave having an inner volume of 200 liters was charged with 250 gof the solid titanium catalyst component-1 obtained in ProductionExample 1, 32.1 g of triethylaluminum (which is denoted sometimes in thefollowing as TEA) and 125 liters of heptane. Then, thereto were charged1250 g of propylene while maintaining the internal temperature at 10° C.and the mixture was agitated for 30 minutes, whereupon 18 g of titaniumtetrachloride were added thereto, whereby prepolymerization catalystcomponent-3 in a form of slurry was obtained.

Production Example 4

To 18 liters of hexane, 2,700 mmol of triethylaluminum, 540 mmol ofdiphenyldimethoxysilane (in the following, sometimed denoted as DPDMS)and 270 mmol, calculated as titanium atom, of the solid titaniumcatalyst component-2 obtained in the above Production Example 2 wereadded at 25° C. Thereto were added then 920 N liters of propylene gasover a period of 1.5 hours to obtain prepolymerization catalystcomponent-4 in a form of slurry.

EXAMPLE 1-1

A polymerization reactor having an internal volume of 3,000 liters wascharged under a nitrogen atmosphere with 1180 liters of heptane, 137grams of diluted triethylaluminum, 279 grams ofdicyclopentyldimethoxysilane (in the following, sometimes abbreviated asDCPMS) and 72 grams of the solid titanium catalyst component-1 obtainedin Production Example 1. After the nitrogen gas in the polymerizationreactor was exhausted using a vacuum pump, the vessel was charged withpropylene, whereupon the temperature of the vessel was started toelevate. At 60° C., propylene was supplied thereto continuously so as tomaintain the internal pressure of the polymerization reactor at 0.64 MPa(6.5 kgf/cm² gauge) and the polymerization was continued for 2.2 hoursunder a condition of substantial absence of hydrogen (the first stagepolymerization was over). By sampling and analyzing a part of the slurryin the polymerization reactor after the completion of the first stagepolymerization, an intrinsic viscosity [η] of 8.7 dl/g was observed.

Then, the temperature was elevated to 70° C. and propylene and hydrogenwere supplied so as to maintain the internal pressure at 0.12 MPa (1.2kgf/cm², gauge) and the hydrogen concentration in the gas phase at 5.1vol. %, whereupon the polymerization was continued for 4 hours (thesecond stage polymerization was over). After the polymerization wasover, 144.3 ml of methanol were added to the reactor to terminate thepolymerization, followed by an ordinary procedure of purification anddrying, whereby 690 kg of a powdery polypropylene resin composition wereobtained. The polypropylene resin composition finally obtained in thisway had, as a whole, a melt flow rate of 0.5 g/10 min. The proportion ofthe polypropylene product produced by the first stage polymerizationrelative to the finally obtained polypropylene resin composition, ascalculated from the material balance, was 30% by weight. Materialproperties of the finally obtained polypropylene resin composition X-1were assessed. The polymerization condition and the results ofassessments are given in Table 1 and Table 8, respectively.

EXAMPLE 1-2

In an autoclave having an internal volume of 600 liters, 200 liters ofpropylene were charged and the temperature thereof was elevated to 60 °C., whereto were added then 0.3 mmol of triethylaluminum. 0.13 mmol ofDCPMS and 0.6 mmol, calculated as titanium atom, of the solid titaniumcatalyst component-2 obtained in Production Example 2. The temperaturewas elevated to 70° C. and the polymerization was caused whilemaintaining this temperature for 20 minutes (the first stagepolymerization was over).

Then, after the temperature was elevated to 70° C. under a hydrogenpartial pressure of 0.05 MPa (0.5 kgf/cm², gauge), this was maintainedfor 35 minutes to effect polymerization. Then, the venting valve wascaused to open so as to purge the unreacted propylene via an integratingflow meter (the second stage polymerization was over). In order toassess the intrinsic viscosity [η] of the resulting polypropyleneproduct obtained in the first stage polymerization, a part of it wassampled and assessed after the first stage polymerization was over,whereby the intrinsic viscosity [η] was found to be 11 dl/g. Theproportion of the polypropylene product produced by the first stagepolymerization relative to the amount of the finally obtainedpolypropylene resin composition was found to be 32% by weight. Materialproperties of the finally obtained polypropylene resin composition X-2were assessed. The polymerization condition and the results ofassessments are given in Table 3 and Table 8, respectively.

EXAMPLE 1-3

The procedures of Example 1-1 were pursued except that the internalpressure of the polymerization reactor of the second stage was changedto 0.098 MPa (1.0 kgf/cm², gauge) and the hydrogen concentration in thegas phase to 14 vol. %, whereby polypropylene resin composition X-3 wasobtained. The polymerization condition and the results of assessmentsare given in Table 1 and Table 8, respectively.

EXAMPLE 1-4

A polymerization reactor-1 having an internal volume of 500 liters wassupplied continuously with 87 liters/hr of heptane, 9.6 grams/hr of theprepolymerization catalyst component-3 obtained in Production Example 3,18.2 grams/hr of triethylaluminum and 37.2 grams/hr of DCPMS, whilesupplying thereto propylene continuously at 60° C. under a condition ofsubstantial absence of hydrogen so as to maintain the internal pressureof the polymerization reactor-1 at 0.69 MPa (7.0 kgf/cm², gauge) (thefirst stage polymerization). By sampling the slurry in thepolymerization reactor-1 and assessing the intrinsic viscosity [η] ofthe polypropylene product, a value of 9.1 dl/g was obtained.

The so-obtained slurry was transferred continuously to a polymerizationreactor-2 having an internal volume of 500 liters to cause furtherpolymerization. The polymerization reactor-2 was supplied with 32liters/hr of heptane, while supplying thereto propylene and hydrogencontinuously at 70° C. so as to maintain the internal pressure of thepolymerization reactor-2 at 0.69 MPa (7.0 kgf/cm², gauge) and thehydrogen gas concentration in the gas phase at 6% by volume (secondstage polymerization).

The slurry discharged out of the polymerization reactor-2 was treated inusual manner, after separation of unreacted monomer, by centrifugationto remove heptane and drying at 80° C. under a pressure of 9,300 Pa (70mm Hg, gauge) for 10 hours to obtain a product. This powdery product wasobtained at a through-put of 80 kg/hr. The melt flow rate of thisproduct was found to be 0.5 g/10 min. The proportion of thepolypropylene product produced by the first stage polymerizationrelative to the amount of the finally obtained polypropylene resincomposition as calculated from the material balance was found to be 30%by weight. Material properties of the finally obtained polypropyleneresin composition X-4 were assessed. The polymerization condition andthe results of assessments are given in Table 4 and Table 8,respectively.

EXAMPLE 1-5

The polymerization was carried out in the same manner as in Example 1-4except that the supply rates of the prepolymerization catalystcomponent-3, triethylaluminum and DCPMS supplied to the polymerizationreactor-1 were changed to 7.4 g/hr, 13.5 g/hr and 28.7 g/hr,respectively, and the feed rate of heptane supplied to thepolymerization reactor-2, the internal pressure and the hydrogenconcentration in the gas phase were changed to 40 liters/hr, 0.59 MPa(6.0 kgf/cm², gauge) and 23 vol. %, respectively, whereby polypropyleneresin composition X-5 was obtained. The reaction condition and theresults of assessments are given in Tables 4 and 8, respectively.

EXAMPLE 1-6

The polymerization was carried out in a continuous two-stage process byusing one reactor in the first stage polymerization and two reactors inthe second stage polymerization. Thus, 151 liters/hr of heptane, 8.9g/hr of the prepolymerization catalyst component-3 obtained inProduction Example 3, 16.9 g/hr of triethylaluminum and 34.5 g/hr ofDCPMS were supplied continuously to polymerization reactor-1 having aninternal volume of 500 liters and thereto was supplied propylenecontinuously at a temperature of 55° C. under a condition of substantialabsence of hydrogen, so as to maintain the internal pressure of thereactor-1 at 0.78 MPa (8.0 kgf/cm², gauge) (the first stagepolymerization). By sampling the slurry in the reactor-1 and assessingthe intrinsic viscosity [η] of the polypropylene product, a value of 9.2dl/g was obtained.

The second stage polymerization was carried out in a continuous processusing two polymerization reactors. Thus, the slurry in thepolymerization reactor-1 which had been subjected to the first stagepolymerization was transferred first to polymerization reactor-2 havingan internal volume of 500 liters continuously to subject it to a furtherpolymerization. The polymerization reactor-2 was supplied continuouslywith heptane at a rate of 14.7 liters/hr, while supplying theretopropylene and hydrogen continuously at a temperature of 70° C. so as tomaintain the internal pressure of the polymerization reactor-2 at 0.78MPa (8.0 kgf/cm², gauge) and the hydrogen concentration in the gas phaseat 6 vol. %. The slurry in the polymerization reactor-2 was thentransferred continuously to polymerization reactor-3 having an internalvolume of 300 liters to subject it to a further polymerization. Thepolymerization reactor-3 was supplied continuously with heptane at arate of 16.4 liters/hr, while supplying thereto propylene and hydrogencontinuously at a temperature of 70° C. so as to maintain the internalpressure of the polymerization reactor-3 at 0.74 MPa (7.5 kgf/cm²,gauge) and the hydrogen concentration in the gas phase at 6 vol. %.

The slurry discharged from the polymerization reactor-3 was treated inusual manner, after separation of unreacted monomer, by centrifugationto remove heptane and drying at 80° C. under a pressure of 9,300 Pa (70mm Hg, gauge) for 10 hours to obtain a product. This powdery product wasobtained at a through-put of 80 kg/hr. The melt flow rate of thisproduct was found to be 0.4 g/10 min. The proportion of thepolypropylene product produced by the first stage polymerizationrelative to the amount of the finally obtained polypropylene resincomposition as calculated from the material balance was found to be 33%by weight. Material properties of the finally obtained polypropyleneresin composition X-6 were assessed. The reaction condition and theresults of assessments are given in Table 4 and Table 9, respectively.

EXAMPLE-1-7

The polymerization was carried out in a continuous two-stage process byusing one reactor in the first stage polymerization and four reactors inthe second stage polymerization. Thus, 53 liters/hr of heptane, 8.0 g/hrof the prepolymerization catalyst component-3 obtained in ProductionExample 3, 15.2 g/hr of triethylaluminum and 31 g/hr of DCPMS weresupplied to polymerization reactor-1 having an internal volume of 500liters and thereto was supplied propylene continuously at a temperatureof 60° C. under a condition of substantial absence of hydrogen, so as tomaintain the internal pressure of the reactor-1 at 0.76 MPa (7.8kgf/cm², gauge) (the first stage polymerization). By sampling the slurryin the reactor-1 and assessing the intrinsic viscosity [η] of thepolypropylene product, a value of 9.5 dl/g was obtained.

The second stage polymerization was carried out in a continuous processusing four polymerization reactors. Thus, the slurry in thepolymerization reactor-1 which had been subjected to the first stagepolymerization was transferred first to polymerization reactor-2 havingan internal volume of 500 liters continuously to subject it to a furtherpolymerization. The polymerization reactor-2 was supplied continuouslywith heptane at a rate of 56 liters/hr, while supplying theretopropylene and hydrogen continuously at a temperature of 70° C. so as tomaintain the internal pressure of the polymerization reactor-2 at 0.21MPa (2.1 kgf/cm², gauge) and the hydrogen concentration in the gas phaseat 6 vol. %. The slurry in the polymerization reactor-2 was thentransferred continuously to polymerization reactor-3 having an internalvolume of 500 liters to subject it to a further polymerization. Thepolymerization reactor-3 was supplied continuously with heptane at arate of 24 liters/hr, while supplying thereto propylene and hydrogencontinuously at a temperature of 70° C. so as to maintain the internalpressure of the polymerization reactor-3 at 0.15 MPa (1.5 kgf/cm²,gauge) and the hydrogen concentration in the gas phase at 6 vol. %. Theslurry in the polymerization reactor-3 was then transferred continuouslyto polymerization reactor-4 having an internal volume of 500 liters tosubject it to a further polymerization. The polymerization reactor-4 wassupplied continuously with heptane at a rate of 17 liters/hr, whilesupplying thereto propylene and hydrogen continuously at a temperatureof 70° C. so as to maintain the internal pressure of the polymerizationreactor-4 at 0.098 MPa (1.0 kgf/cm², gauge) and the hydrogenconcentration in the gas phase at 6 vol. %. The slurry in thepolymerization reactor-4 was then transferred continuously topolymerization reactor-5 having an internal volume of 300 liters tosubject it to a further polymerization. The polymerization reactor-5 wassupplied continuously with heptane at a rate of 10 liters/hr, whilesupplying thereto propylene and hydrogen continuously at a temperatureof 70° C. so as to maintain the internal pressure of the polymerizationreactor-5 at 0.020 MPa (0.20 kgf/cm², gauge) and the hydrogenconcentration in the gas phase at 6 vol. %.

The slurry discharged from the polymerization reactor-5 was treated inusual manner, after separation of unreacted monomer, by centrifugationto remove heptane and drying at 80° C. under a pressure of 9,300 Pa (70mm Hg, gauge) for 10 hours to obtain a product. This powdery product wasobtained at a through-put of 78 kg/hr. The melt flow rate of thisproduct was found to be 0.5 g/10 min. The proportion of thepolypropylene product produced by the first stage polymerizationrelative to the amount of the finally obtained polypropylene resincomposition as calculated from the material balance was found to be 32%by weight. Material properties of the finally obtained polypropyleneresin composition X-7 were assessed. The reaction condition and theresults of assessments are given in Table 4 and Table 9, respectively.

EXAMPLE 1-8

The polymerization was carried out in the same manner as in Example 1-7except that, in the first place, the supply rates of theprepolymerization catalyst component-3, triethylaluminum and DCPMSsupplied to the polymerization reactor-1 were changed to 5.4 g/hr, 10.3g/hr and 20.9 g/hr, respectively, in the second place, the feed rate ofheptane supplied to the polymerization reactor-2, the internal pressureand the hydrogen concentration in the gas phase were changed to 70liters/hr, 0.61 MPa (6.2 kgf/cm², gauge) and 30 vol. %, respectively, inthe third place, the feed rate of heptane supplied to the polymerizationreactor-3 and the internal pressure were changed to 10 liters/hr and0.47 MPa (4.8 kgf/cm², gauge), respectively, in the fourth place, thefeed rate of heptane supplied to the polymerization reactor-4, theinternal pressure and the hydrogen concentration in the gas phase werechanged to 15 liters/hr, 0.52 MPa (5.3 kgf/cm², gauge) and 30 vol. %,respectively, and in the fifth place, the feed rate of heptane suppliedto the polymerization reactor-5, the internal pressure and the hydrogenconcentration in the gas phase were changed to 10 liters/hr, 0.32 MPa(3.3 kgf/cm², gauge) and 30 vol. %, respectively, whereby polypropyleneresin composition X-8 was obtained. The reaction condition and theresults of assessments are given in Tables 5 and 9, respectively.

EXAMPLE 1-9

The polymerization was carried out as in Example 1-1 except that theinternal pressure and the polymerization duration in the reactor of thefirst stage polymerization were changed to 0.49 MPa (5.0 kgf/cm², gauge)and 3.0 hours, respectively, and the internal pressure of thepolymerization reactor and the hydrogen concentration in the gas phasein the second stage polymerization were changed to 0.20 MPa (2.0kgf/cm², gauge) and 25 vol. %, respectively, whereby polypropylene resincomposition X-9 was obtained. The reaction condition and the results ofassessments are given in Table 1 and Table 9, respectively.

EXAMPLE 1-10

The polymerization was carried out as in Example 1-2 except that thepolymerization temperature and the polymerization duration in the firststage polymerization were changed to 70° C. and 25 minutes,respectively, and the polymerization temperature, polymerizationduration and the hydrogen partial pressure in the second stagepolymerization were changed to 70° C., 35 minutes and 0.07 MPa (0.7kgf/cm², gauge), respectively, whereby polypropylene resin compositionX-10 was obtained. The reaction condition and the results of assessmentsare given in Table 3 and Table 9, respectively.

EXAMPLE 1-11

The polymerization was carried out as in Example 1-1 except that theinternal pressure of the polymerization reactor and the polymerizationduration in the first stage polymerization were changed to 0.49 MPa (5.0kgf/cm², gauge) and 1.5 hours, respectively, and the internal pressureof the polymerization reactor, the hydrogen concentration in the gasphase and the polymerization duration in the second stage polymerizationwere changed to 0.18 MPa (1.8 kgf/cm², gauge), 0.7 vol. % and 5.0 hours,respectively, whereby polypropylene resin composition X-11 was obtained.The reaction condition and the results of assessments are given in Table1 and Table 10, respectively.

EXAMPLE 1-12

The polymerization was carried out as in Example 1-1 except that theinternal pressure of the polymerization reactor and the polymerizationduration in the first stage polymerization were changed to 0.49 MPa (5.0kgf/cm², gauge) and 1.5 hours, respectively, and the internal pressureof the polymerization reactor, the hydrogen concentration in the gasphase and the polymerization duration in the second stage polymerizationwere changed to 0.13 MPa (1.3 kgf/cm², gauge), 19 vol. % and 5.0 hours,respectively, whereby polypropylene resin composition X-12 was obtained.The reaction condition and the results of assessments are given in Table1 and Table 10, respectively.

EXAMPLE 1-13

The polymerization was carried out as in Example 1-1 except that theinternal pressure of the polymerization reactor and the polymerizationduration in the first stage polymerization were changed to 0.49 MPa (5.0kgf/cm², gauge) and 1.8 hours, respectively, and the internal pressureof the polymerization reactor, the hydrogen concentration in the gasphase and the polymerization duration in the second stage polymerizationwere changed to 0.26 MPa (2.7 kgf/cm², gauge), 29 vol. % and 3.8 hours,respectively, whereby polypropylene resin composition X-13 was obtained.The reaction condition and the results of assessments are given in Table1 and Table 10, respectively.

EXAMPLE 1-14

The polymerization was carried out as in Example 1-1 except that theinternal pressure of the polymerization reactor and the polymerizationduration in the first stage polymerization were changed to 0.49 MPa (5.0kgf/cm², gauge) and 2.0 hours, respectively, and the internal pressureof the polymerization reactor, the hydrogen concentration in the gasphase and the polymerization duration in the second stage polymerizationwere changed to 0.24 MPa (2.4 kgf/cm², gauge), 0.2 vol. % and 5.0 hours,respectively, whereby polypropylene resin composition X-14 was obtained.The reaction condition and the results of assessments are given in Table2 and Table 10, respectively.

EXAMPLE 1-15

The polymerization was carried out as in Example 1-2 except that thepolymerization temperature and the polymerization duration in the firststage polymerization were changed to 40° C. and 30 minutes,respectively, and the polymerization temperature and the polymerizationduration in the second stage polymerization were changed to 40° C. and45 minutes, respectively, whereby polypropylene resin composition X-15was obtained. The reaction condition and the results of assessments aregiven in Table 3 and Table 10, respectively.

EXAMPLE 1-16

The polymerization was carried out as in Example 1-1 except that theinternal pressure of the polymerization reactor and the polymerizationduration in the first stage polymerization were changed to 0.49 MPa (5.0kgf/cm², gauge) and 3.5 hours, respectively, and the internal pressureof the polymerization reactor, the hydrogen concentration in the gasphase and the polymerization duration in the second stage polymerizationwere changed to 0.24 MPa (2.4 kgf/cm², gauge), 27 vol. % and 3.7 hours,respectively, whereby polypropylene resin composition X-16 was obtained.The reaction condition and the results of assessments are given in Table2 and Table 10, respectively.

Comparative Example 1-1

A polymerization reactor having an internal volume of 3,000 liters wascharged under a nitrogen atmosphere with 1180 liters of heptane, 125grams of diluted triethylaluminum, 217 grams of DCPMS and 55 grams ofthe solid titanium catalyst component-1 obtained in ProductionExample 1. After the nitrogen gas in the polymerization reactor wasexhausted using a vacuum pump, the reactor was charged with propylene,whereupon the temperature of the reactor was started to elevate. At 70 °C., propylene and hydrogen were supplied thereto continuously so as tomaintain the internal pressure of the polymerization reactor at 0.74 MPa(7.5 kgf/cm² gauge) and the hydrogen concentration in the gas phase at0.3 vol. %, whereupon the polymerization was continued for 6.0 hours.After the polymerization was over, 144.3 ml of methanol were added tothe reactor to terminate the polymerization, followed by an ordinaryprocedure of purification and drying, whereby 700 kg of a powderypolypropylene resin composition were obtained. The polypropylene resincomposition X-17 finally obtained in this way had, as a whole, a meltflow rate of 0.5 g/10 min. The reaction condition and the results ofassessments are given in Table 6 and Table 11, respectively.

Comparative Example 1-2

The polymerization was carried out as in Comparative Example 1-1 exceptthat the internal pressure of the polymerization reactor, the hydrogenconcentration in the gas phase and the polymerization duration werechanged to 0.88 MPa (9.0 kgf/cm², gauge), 0.1 vol. % and 7.0 hours,respectively, whereby polypropylene resin composition X-18 was obtained.The reaction condition and the results of assessments are given in Table6 and Table 11, respectively.

Comparative Example 1-3

The polymerization was carried out as in Comparative Example 1-1 exceptthat the internal pressure of the polymerization reactor, the hydrogenconcentration in the gas phase and the polymerization duration werechanged to 0.59 MPa (6.0 kgf/cm², gauge), 2 vol. % and 5.0 hours,respectively, whereby polypropylene resin composition X-19 was obtained.The reaction condition and the results of assessments are given in Table6 and Table 11, respectively.

Comparative Example 1-4

The polymerization was carried out as in Example 1-1 except that theinternal pressure and the polymerization duration in the first stagepolymerization were changed to 0.49 MPa (5.0 kgf/cm², gauge) and 2.0hours, respectively, and the internal pressure of the polymerizationreactor, the hydrogen concentration in the gas phase and thepolymerization duration in the second stage polymerization were changedto 0.27 MPa (2.8 kgf/cm², gauge), 32 vol. % and 3.7 hours, respectively,whereby polypropylene resin composition X-20 was obtained. The reactioncondition and the results of assessments are given in Table 2 and Table11, respectively.

Comparative Example 1-5

The polymerization was carried out as in Example 1-4 except that theinternal pressure of the polymerization reactor-2 and the hydrogenconcentration in the gas phase were changed to 0.59 MPa (6.0 kgf/cm²,gauge) and 29 vol. %, respectively, whereby polypropylene resincomposition X-21 was obtained. The reaction condition and the results ofassessments are given in Table 5 and Table 11, respectively.

Comparative Example 1-6

The polymerization was carried out as in Example 1-1 except that theinternal pressure and the polymerization duration in the first stagepolymerization were changed to 0.49 MPa (5.0 kgf/cm², gauge) and 2.0hours, respectively, and the internal pressure of the polymerizationreactor, the hydrogen concentration in the gas phase and thepolymerization duration in the second stage polymerization were changedto 0.25 MPa (2.6 kgf/cm², gauge), 27 vol. % and 3.9 hours, respectively,whereby polypropylene resin composition X-22 was obtained. The reactioncondition and the results of assessments are given in Table 2 and Table12, respectively.

Comparative Example 1-7

A polymerization reactor having an internal volume of 3,000 liters wascharged under a nitrogen atmosphere with 1180 liters of heptane, 164grams of diluted triethylaluminum, 284 grams of DCPMS and 72 grams ofthe solid titanium catalyst component-1 obtained in ProductionExample 1. After the nitrogen gas in the polymerization reactor wasexhausted using a vacuum pump, the reactor was charged with propylene,whereupon the temperature of the reactor was started to elevate. At 60°C., propylene and hydrogen were supplied thereto continuously so as tomaintain the internal pressure of the polymerization reactor at 0.32 MPa(3.3 kgf/cm², gauge) and the hydrogen concentration in the gas phase at0.03 vol. %, whereupon the polymerization was continued for 3.0 hours.By sampling and analyzing a part of the slurry in the polymerizationreactor after the completion of the first stage polymerization, anintrinsic viscosity [η] of 3.9 dl/g was observed (the first stagepolymerization was over).

Then, the temperature was elevated to 70° C. and propylene and hydrogenwere supplied continuously so as to maintain the internal pressure at0.16 MPa (1.6 kgf/cm², gauge) and the hydrogen concentration in the gasphase at 6 vol. %, whereupon the polymerization was continued for 4.4hours (the second stage polymerization was over). After thepolymerization was over, 144.3 ml of methanol were added to the reactorto terminate the polymerization, followed by ordinary procedures ofpurification and drying, whereby 680 kg of a powdery polypropylene resincomposition were obtained. The polypropylene resin composition finallyobtained in this way had, as a whole, a melt flow rate of 0.5 g/10 min.The proportion of the polypropylene product produced by the first stagepolymerization relative to the finally obtained polypropylene resincomposition, as calculated from the material balance, was 50% by weight.Material properties of the finally obtained polypropylene resincomposition X-23 were assessed. The reaction condition and the resultsof assessments are given in Table 2 and Table 12, respectively.

Comparative Example 1-8

A polymerization reactor having an internal volume of 3,000 liters wascharged under a nitrogen atmosphere with 1180 liters of heptane, 164grams of diluted triethylaluminum, 284 grams of DCPMS and 144 grams ofthe solid titanium catalyst component-1 obtained in ProductionExample 1. After the nitrogen gas in the polymerization reactor wasexhausted using a vacuum pump, the reactor was charged with propylene,whereupon the temperature of the reactor was started to elevate. At 60°C., propylene was supplied thereto continuously so as to maintain theinternal pressure of the polymerization reactor at 0.78 MPa (8.0kgf/cm², gauge), whereupon the polymerization was continued for 2.5hours. After the polymerization was over, 144.3 ml of methanol wereadded to the reactor to terminate the polymerization, followed by anordinary procedure of purification and drying, whereby 670 kg of apowdery polypropylene resin composition X-24 were obtained. The reactioncondition and the results of assessments are given in Table 6 and Table12, respectively.

Comparative Example 1-9

An autoclave having an internal volume of 3,000 liters was charged undera nitrogen atmosphere with 1180 liters of heptane, 164 grams of dilutedtriethylaluminum, 284 grams of DCPMS and 138 grams of the solid titaniumcatalyst component-1 obtained in Production Example 1. After thenitrogen gas in the polymerization reactor was exhausted using a vacuumpump, the reactor was charged with propylene, whereupon the temperatureof the reactor was started to elevate. At 70° C., propylene and hydrogenwere supplied thereto continuously so as to maintain the internalpressure of the polymerization reactor at 0.88 MPa (9.0 kgf/cm² gauge)and the hydrogen concentration in the gas phase at 6 vol. %, whereuponthe polymerization was continued for 6.0 hours. After the polymerizationwas over, 144.3 ml of methanol were added to the reactor to terminatethe polymerization, followed by an ordinary procedure of purificationand drying, whereby 690 kg of a powdery polypropylene resin compositionX-25 were obtained. The reaction condition and the results ofassessments are given in Table 6 and Table 12, respectively.

Comparative Example 1-10

Polymerization of a lower molecular weight polypropylene was carried outusing two polymerization reactors in the first stage polymerization.Thus, a polymerization reactor-1 having an internal volume of 300 literswas supplied continuously with heptane at a rate of 74 liters/hr, theprepolymerization catalyst component-3 as the catalyst at a rate of 10.4g/hr, triethylaluminum at a rate of 19.8 g/hr and DCPMS at a rate of40.3 g/hr, while supplying thereto at a temperature of 70° C. propyleneand hydrogen continuously so as to maintain the internal pressure of thepolymerization reactor at 0.59 MPa (6.0 kgf/cm², gauge) and the hydrogenconcentration in the gas phase at 2.0 vol. %. Then, the slurry in thepolymerization reactor-1 was transferred to a polymerization reactor-2having an internal volume of 500 liters continuously to subject it to afurther polymerization. The polymerization reactor-2 was supplied withheptane at a rate of 71 liters/hr, while supplying thereto propylene andhydrogen continuously at a temperature of 70° C. so as to maintain theinternal pressure of the polymerization reactor-2 at 0.49 MPa (5.0kgf/cm², gauge) and the hydrogen concentration in the gas phase at 2.0vol. %. By sampling the slurries of the reactor-1 and the reactor-2 toassess the intrinsic viscosity [η] of each of the polymers, a value of1.9 dl/g was observed for each.

The slurry in the polymerization reactor-2 was then transferredcontinuously to a dehydrogenating vessel having an internal volume of 70liters to purge the unreacted propylene and hydrogen continuously. Theslurry in the dehydrogenating vessel was transferred to polymerizationreactor-3 continuously to effect the second stage polymerization of highmolecular weight polypropylene. The polymerization ractor-3 was suppliedwith heptane at a rate of 10 liters/hr, while supplying theretopropylene continuously at a temperature of 60° C. so as to maintain theinternal pressure of the polymerization reactor at 0.78 MPa (8.0kgf/cm², gauge).

The slurry discharged from the polymerization reactor-3 was treated inusual manner, after separation of unreacted monomer, by centrifugationto remove heptane and drying at 80° C. under a pressure of 9,300 Pa (70mm Hg, gauge) for 10 hours to obtain a product. This powdery product wasobtained at a through-put of 81 kg/hr. The melt flow rate of thisproduct was found to be 0.5 g/10 min. The proportion of thepolypropylene product produced in the polymerization reactor-3 of thesecond stage polymerization relative to the amount of the finallyobtained polypropylene resin composition as calculated from the materialbalance was found to be 30% by weight and the intrinsic viscosity [η]thereof was found to be 7.2 dl/g. Material properties of the finallyobtained polypropylene resin composition X-26 were assessed. Thereaction condition and the results of assessments are given in Table 5and Table 12, respectively.

Comparative Example 1-11

30 parts by weight of the polypropylene resin composition X-24 obtainedin Comparative Example 1-8 and 70 parts by weight of the polypropyleneresin composition X-25 obtained in Comparative Example 1-9 were blendedtogether with a predetermined stabilizer and the resulting blend waskneaded and extruded on a monoaxial extruder (a machine of IshinakaTekkojo K.K.) at a temperature of 240° C., whereby polypropylene resincomposition X-27 was obtained. Results are given in Table 13.

Comparative Example 1-12

A polymerization reactor having an internal volume of 3,000 liters wascharged under a nitrogen atmosphere with 1180 liters of heptane, 148grams of diluted diethylaluminum chloride and 118 grams of a titaniumtrichloride catalyst supplied from NIPPON SOLVAY K.K. After the nitrogengas in the polymerization reactor was exhausted using a vacuum pump, thereactor was charged with propylene, whereupon the temperature of thereactor was started to elevate. At 60° C., propylene and hydrogen weresupplied thereto continuously so as to maintain the internal pressure ofthe polymerization reactor at 0.78 MPa (8.0 kgf/cm², gauge) and thehydrogen concentration in the gas phase at 12 vol. %, whereupon thepolymerization was continued for 3.0 hours. By sampling and analyzing apart of the slurry in the polymerization reactor, an intrinsic viscosity[η] of 1.1 dl/g was observed (the first stage polymerization was over).

Then, the unreacted propylene and hydrogen in the polymerization reactorwere once purged. Thereafter, the temperature was settled at 50° C. andpropylene was supplied continuously so as to maintain the internalpressure at 0.69 MPa (7.0 kgf/cm², gauge), whereupon the polymerizationwas continued for 4.0 hours (the second stage polymerization was over).After the polymerization was over, 144.3 ml of methanol were added tothe reactor to terminate the polymerization, followed by an ordinaryprocedure of purification and drying, whereby 120 kg of a powderypolypropylene resin composition were obtained. The resultingpolypropylene resin composition had, as a whole, a melt flow rate of 0.4g/10 min. The proportion of the polypropylene product produced in thesecond stage polymerization relative to the finally obtainedpolypropylene resin composition, as calculated from the materialbalance, was 40% by weight and the intrinsic viscosity [η] thereof wasfound to be 10.0 dl/g. Material properties of the finally obtainedpolypropylene resin composition X-28 were assessed. The reactioncondition and the results of assessments are given in Table 2 and Table13, respectively.

Comparative Example 1-13

To a polymerization reactor-1 having an internal volume of 250 liters,there were supplied continuously the prepolymerization catalystcomponent-4 obtained in Production Example 4 in a form of a hexaneslurry at a rate of 0.56 mmol/hr as titanium atom, triethylaluminum in aform of a hexane solution at a rate of 28 mmol/hr,diphenyldimethoxysilane in a form of a hexane solution at a rate of 2.8mmol/hr and hexane in a rate to sum up to 27.3 liters/hr of the totalfeed, while supplying thereto propylene continuously at such a rate asto maintain the inner pressure of the polymerization reactor-1 at 1.2MPa (12 kgf/cm², gauge) to effect polymerization at a temperature of 70°C. (the first stage polymerization). By sampling the slurry in thepolymerization reactor-1 and assessing the intrinsic viscosity [η]thereof, a value of 7.1 dl/g was obtained.

The slurry in the polymerization reactor-1 which had been subjected tothe first stage polymerization was transferred to polymerizationreactor-2 having an internal volume of 250 liters continuously tosubject it to a further polymerization. The polymerization reactor-2 wassupplied continuously with propylene and hexane at a total rate of 11liters/hr to effect polymerization at a temperature of 70° C. Bysupplying hydrogen thereto continuously, the intrinsic viscosity [η] wasadjusted (the second stage polymerization).

The slurry discharged from the polymerization reactor-2 was treated inusual manner, after separation of unreacted monomer, by centrifugationto remove heptane and drying at 80° C. under a pressure of 9,300 Pa (70mm Hg, gauge) for 10 hours to obtain a product. The melt flow rate ofthis product was found to be 0.5 g/10 min. The proportion of thepolypropylene product produced in the first stage polymerizationrelative to the amount of the finally obtained polypropylene resincomposition as calculated from the material balance was found to be 35%by weight. Material properties of the finally obtained polypropyleneresin composition X-29 were assessed. The reaction condition and theresults of assessments are given in Table 7 and Table 13, respectively.

Comparative Example 1-14

The procedures of Comparative Example 13 were traced except that thereaction rate and the intrinsic viscosity [η] for each polymerizationstage were altered. Material properties of the finally obtainedpolypropylene resin composition X-30 were assessed. The reactionscondition and the results of assessments are given in Table 7 and Table13, respectively.

TABLE 1 Reaction Condition Example 1-1 1-3 1-9 1-11 1-12 1-13Polypropylene Resin Composition X-1 X-3 X-9 X-11 X-12 X-13 1st StagePolymerization Amount of heptane charged (liter) 1180 1180 1180 11801180 1180 Organometallic compound used TEA TEA TEA TEA TEA TEA amount(g) 137 137 137 137 137 137 Titanium catalyst component used comt. 1comt. 1 comt. 1 comt. 1 comt. 1 comt. 1 amount (g) 72 72 72 72 72 72Organosilicic compound used DCPMS DCPMS DCPMS DCPMS DCPMS DCPMS amount(g) 279 279 279 279 279 279 Polymerization temperature (° C.) 60 60 6060 60 60 pressure (MPa, gauge) 0.64 0.64 0.49 0.49 0.49 0.49 H₂ conc. inthe gas phase (vol. %) 0 0 0 0 0 0 Polymerization duration (hr) 2.2 2.23.0 1.5 1.5 1.8 2nd Stage Polymerization Polymerization temperature (°C.) 70 70 70 70 70 70 pressure (MPa, gauge) 0.12 0.098 0.20 0.18 0.130.26 H₂ conc. in the gas phase (vol. %) 5.1 14 25 0.7 19 29Polymerization duration (hr) 4.0 4.0 4.0 5.0 5.0 3.8 Notes: TEA =triethylaluminum DEAC = diethylaluminum chloride DCPMS =dicyclopentyldimethoxysilane

TABLE 2 Reaction Condition Example Comparative Example 1-14 1-16 1-4 1-61-7 1-12 Polypropylene Resin Composition X-14 X-16 X-20 X-22 X-23 X-281st Stage Polymerization Amount of heptane charged (liter) 1180 11801180 1180 1180 1180 Organometallic compound used TEA TEA TEA TEA TEADEAC amount (g) 1137 137 137 137 164 148 Titanium catalyst componentused comt. 1 comt. 1 comt. 1 comt. 1 comt. 1 TiCl₃ amount (g) 72 72 7272 72 118 Organosilicic compound used DCPMS DCPMS DCPMS DCPMS DCPMS nonamount (g) 279 279 279 279 284 0 Polymerization temperature (° C.) 60 6060 60 60 60 pressure (MPa, gauge) 0.49 0.49 0.49 0.49 0.32 0.78 H₂ conc.in the gas phase (vol. %) 0 0 0 0 0.03 12 Polymerization duration (hr)2.0 3.5 2.0 2.0 3.0 3.0 2nd Stage Polymerization Polymerizationtemperature (° C.) 70 70 70 70 70 50 pressure (MPa, gauge) 0.24 0.240.27 0.25 0.16 0.69 H₂ conc. in the gas phase (vol. %) 0.2 27 32 27 6 0Polymerization duration (hr) 5.0 3.7 3.7 3.9 4.4 4.0 Notes: TEA =triethylaluminum DEAC = diethylaluminum chloride DCPMS =dicyclopentyldimethoxysilane

TABLE 3 Reaction Condition Example 1-2 1-10 1-15 Polypropylene ResinComposition X-2 X-10 X-15 1st Stage Polymerization Amount of propylenecharged (liter) 200 200 200 Triethylaluminum amount (mmol) 0.3 0.3 0.3DCPMS amount (mmol) 0.13 0.13 0.13 Titanium catalyst component usedcompot. 2 compot. 2 compot. 2 amount (mmol) *⁾ 0.6 0.6 0.6Polymerization temperature (° C.) 70 70 40 pressure (MPa, gauge) — — —duration (min.) 20 25 30 2nd Stage Polymerization Polymerizationtemperature (° C.) 70 70 40 pressure (MPa, gauge) — — — Hydrogen partialpressure (MPa, gauge) 0.05 0.07 0.05 Polymerization duration (min.) 3535 45 Notes: DCPMS = dicyclopentyldimethoxysilane *⁾calculated astitanium atom

TABLE 4 Example 1-4 1-5 1-6 1-7 Polypropylene resin composition X-4 X-5X-6 X-7 Prepolymerization Solid titanium catalyst component Compont.-1Compont.-1 Compont.-1 Compont.-1 Prepolymerization temperature (° C.) 1010 10 10 Polymerization Reactor-1 Supply rate of heptane (lit./hr) 87 87151 53 Supply rate of prepolym. catalyst (g/hr) 9.6 7.4 8.9 8.0 Supplyrate of triethylaluminum (g/hr) 18.2 13.5 16.9 15.2 Supply rate of DCPMS(g/hr) 37.2 28.7 34.5 31 Polymerization temperature (° C.) 60 60 55 60Polymerization pressure (MPa) 0.69 0.69 0.78 0.76 H₂-concentration ingas phase (vol. %) 0 0 0 0 Polymerization reactor-2 Supply rate ofheptane (lit./hr) 32 40 14.7 56 Polymerization temperature (° C.) 70 7070 70 Polymerization pressure (MPa) 0.69 0.59 0.78 0.21 H₂-concentrationin gas phase (vol. %) 6 23 6 6 Polymerization reactor-3 Supply rate ofheptane (lit./hr) — — 16.4 24 Polymerization temperature (° C.) — — 7070 Polymerization pressure (MPa) — — 0.74 0.15 H₂-concentration in gasphase (vol. %) — — 6 6 Polymerization reactor-4 Supply rate of heptane(lit./hr) — — — 17 Polymerization temperature (° C.) — — — 70Polymerization pressure (MPa) — — — 0.098 H₂-concentration in gas phase(vol. %) — — — 6 Polymerization reactor-5 Supply rate of heptane(lit./hr) — — — 10 Polymerization temperature (° C.) — — — 70Polymerization pressure (MPa) — — — 0.020 H₂-concentration in gas phase(vol. %) — — — 6 DCPMS: dicyclopentyldimethoxysilane

TABLE 5 Example Comparative Example 1-8 1-5 1-10 Polypropylene resincomposition X-8 X-21 X-26 Prepolymerization Solid titanium catalystcomponent Compont.-1 Compont.-1 Compont.-1 Prepolymerization temperature(° C.) 10 10 10 Polymerization Reactor-1 Supply rate of heptane(lit./hr) 53 87 74 Supply rate of prepolym. catalyst (g/hr) 5.4 9.6 10.4Supply rate of triethylaluminum (g/hr) 10.3 18.2 19.8 Supply rate ofDCPMS (g/hr) 20.9 37.2 40.3 Polymerization temperature (° C.) 60 60 70Polymerization pressure (MPa) 0.76 0.69 0.59 H₂-concentration in gasphase (vol. %) 0 0 2 Polymerization reactor-2 Supply rate of heptane(lit./hr) 70 32 71 Polymerization temperature (° C.) 70 70 70Polymerization pressure (MPa) 0.61 0.59 0.49 H₂-concentration in gasphase (vol. %) 30 29 2 Polymerization reactor-3 Supply rate of heptane(lit./hr) 10 — 10 Polymerization temperature (° C.) 70 — 60Polymerization pressure (MPa) 0.47 — 0.78 H₂-concentration in gas phase(vol. %) 6 — 0.05 Polymerization reactor-4 Supply rate of heptane(lit./hr) 15 — — Polymerization temperature (° C.) 70 — — Polymerizationpressure (MPa) 0.52 — — H₂-concentration in gas phase (vol. %) 30 — —Polymerization reactor-5 Supply rate of heptane (lit./hr) 10 — —Polymerization temperature (° C.) 70 — — Polymerization pressure (MPa)0.32 — — H₂-concentration in gas phase (vol. %) 30 — — DCPMS:dicyclopentyldimethoxysilane

TABLE 6 Reaction Condition Comparative Example 1-1 1-2 1-3 1-8 1-9Polypropylene Resin Composition X-17 X-18 X-19 X-24 X-25 PolymerizationReactor-1 Amount of heptane charge (liter) 1180 1180 1180 1180 1180Amount of triethylaluminum (gram) 125 125 125 164 164 Organosiliciccompound used DCPMS DCPMS DCPMS DCPMS DCPMS charged amount (gram) 217217 217 284 284 Titanium catalyst component used compt.-1 compt.-1compt.-1 compt.-1 compt.-1 charged amount (gram) 55 55 55 144 138Polymerization temperature (° C.) 70 70 70 60 70 Polymerization pressure(MPa, gauge) 0.74 0.88 0.59 0.78 0.88 H₂-concentration in gas phase(vol. %) 0.3 0.1 2 0 6 Polymerization duration (hr) 6.0 7.0 5.0 2.5 6.0DCPMS = dicyclopentyldimethoxysilane

TABLE 7 Reaction Condition Comparative Example 1-13 1-14 PolypropyleneResin Composition X-29 X-30 Prepolymerization Titanium catalystcomponent used Compont.-2 Compont.-2 charged amount (mmol) *⁾ 270 270TEA (mmol) 2700 2700 DPDMS (mmol) 540 540 Prepolymerization duration(hr) 1.5 1.5 Prepolymerization tempera- (° C.) 25 25 ture PolymerizationReactor-1 Supply rate of hexane (l/hr) 27.3 27.3 Supply rate ofprepolym. (mmol/hr) *⁾ 0.56 0.56 catalyst Supply rate of TEA (mmol/hr)28 28 Supply rate of DPDMS (mmol/hr) 2.8 2.8 Polymerization tempera- (°C.) 70 70 ture Polymerization pressure (MPa, gauge) 1.2 1.2 H₂concentration in gas (vol. %) 0 0 phase Polymerization Reactor-2 Supplyrate of propylene + (l/hr) 11 11 hexane Polymerization tempera- (° C.)70 70 ture Notes: *⁾calculated as titanium atom TEA = triethylaluminumDPDMS = diphenyldimethoxysilane

TABLE 8 Example 1-1 1-2 1-3 1-4 1-5 Polypropylene Resin Composition X-1X-2 X-3 X-4 X-5 Melt flow rate (g/10 min) ¹⁾ 0.5 0.6 1.6 0.5 4.2 Intri.viscos. of high mol. wt. PP (dl/g) ²⁾ 8.7 11.0 9.1 9.1 9.3 Cont. of highmol. wt. PP (wt. %) 30 32 30 30 26 Number of gels (per 450 cm²) ³⁾ 4 1015 718 2858 (mmmm) fraction (%) ⁴⁾ 98.4 98.2 98.3 98.4 98.2 Mw/Mn (−) ⁵⁾11.5 9.9 14.0 10.5 18.0 Mz/Mw (−) ⁶⁾ 4.1 4.5 5.2 4.3 5.5 Proportion ofhigh mol. wt. part (%) ⁷⁾ 14 16 15 15 12 S_(H)/S_(L) (−) ⁸⁾ 1.44 1.491.46 1.42 1.51 Melt tension (g) ⁹⁾ 12.1 10.8 6.6 11.5 5.7 Criticalshearing rate (sec⁻¹) ¹⁰⁾ 1.82 × 10² 9.12 × 10² 1.82 × 10³ 1.82 × 10²6.57 × 10² Value calculated from formula (I) (−) ¹¹⁾ 7.4 0.6 −2.2 7.42.0 Frexural modulus (MPa) ¹²⁾ 1846 1716 1798 1920 2056 Method ofproduction 2 stage, 2 stage, 2 stage, 2 stage, 2 stage, batch, batch,batch, cont., cont., slurry bulk slurry slurry slurry

TABLE 9 Example 1-6 1-7 1-8 1-9 1-10 Polypropylene Resin Composition X-6X-7 X-8 X-9 X-10 Melt flow rate (g/10 min) ¹⁾ 0.4 0.5 4.0 0.7 0.4 Intri.viscos. of high mol. wt. PP (dl/g) ²⁾ 9.2 9.5 9.4 9.6 9.6 Cont. of highmol. wt. PP (wt. %) 33 32 25 42 37 Number of gels (per 450 cm²) ³⁾ 665340 873 9 8 (mmmm) fraction (%) ⁴⁾ 98.3 98.3 98.3 98.2 98.3 Mw/Mn (−) ⁵⁾14.4 9.8 18.9 19.0 6.3 Mz/Mw (−) ⁶⁾ 3.8 4.0 5.6 4.8 4.0 Proportion ofhigh mol. wt. part (%) ⁷⁾ 15 16 13 20 18 S_(H)/S_(L) (−) ⁸⁾ 1.42 1.431.53 1.45 1.43 Melt tension (g) ⁹⁾ 14.4 12.2 5.6 10.6 10.8 Criticalshearing rate (sec⁻¹) ¹⁰⁾ 1.82 × 10² 1.82 × 10² 6.57 × 10² 1.22 × 10²1.22 × 10² Value calculated from formula (I) (−) ¹¹⁾ 7.4 7.4 2.0 9.0 9.0Frexural modulus (MPa) ¹²⁾ 2067 1949 2064 1849 1700 Method of production2 stage, 2 stage, 2 stage, 2 stage, 2 stage, cont., cont., cont., batch,batch, slurry ¹³⁾ slurry ¹⁴⁾ slurry ¹⁴⁾ slurry bulk Notes: ¹³⁾The secondstage polymerization was carried out using two polymerization reactorsin a continuous process. ¹⁴⁾The second stage polymerization was carriedout using four polymerization reactors in a continuous process.

TABLE 10 Example 1-11 1-12 1-13 1-14 1-15 1-16 Polypropylene ResinComposition X-11 X-12 X-13 X-14 X-15 X-16 Melt flow rate (g/10 min) ¹⁾0.5 3.8 4.0 0.1 0.5 0.5 Intri. viscos. of high mol. wt. PP (dl/g) ²⁾ 8.99.6 9.4 8.9 9.2 9.4 Cont. of high mol. wt. PP (wt. %) 18 18 25 30 29 47Number of gels (per 450 cm²) ³⁾ 5 17 20 3 5 6 (mmmm) fraction (%) ⁴⁾98.4 98.3 98.2 98.4 97.3 98.4 Mw/Mn (−) ⁵⁾ 8.3 17.2 18.9 6.8 10.9 9.0Mz/Mw (−) ⁶⁾ 3.7 4.3 5.6 3.9 4.2 3.7 Proportion of high mol. wt. part(%) ⁷⁾ 9 10 12 19 14 30 S_(H)/S_(L) (−) ⁸⁾ 1.50 1.51 1.53 1.39 1.43 1.53Melt tension (g) ⁹⁾ 8.7 5.3 5.6 19.5 11.4 25.4 Critical shearing rate(sec⁻¹) ¹⁰⁾ 1.82 × 10² 6.57 × 10² 6.57 × 10² 6.57 × 10¹ 6.57 × 10² 6.57× 10¹ Value calculated from formula (I) (−) ¹¹⁾ 7.4 2.0 2.0 11.6 2.011.6 Frexural modulus (MPa) ¹²⁾ 1813 1850 2064 1805 1621 1945 Method ofproduction 2 stage, 2 stage, 2 stage, 2 stage, 2 stage, 2 stage, batch,batch, batch, batch, batch, batch, slurry slurry slurry slurry slurryslurry

TABLE 11 Comparative Example 1-1 1-2 1-3 1-4 1-5 Polypropylene ResinComposition X-17 X-18 X-19 X-20 X-21 Melt flow rate (g/10 min) ¹⁾ 0.50.2 3.5 6.2 5.9 Intri. viscos. of high mol. wt. PP (dl/g) ²⁾ — — — 8.99.2 Content of high mol. wt. PP (wt. %) 0 0 0 30 29 Number of gels (per450 cm²) ³⁾ 4 5 3 25 3510 (mmmm) fraction (%) ⁴⁾ 98.4 98.2 98.2 98.198.1 Mw/Mn (—) ⁵⁾ 5.1 4.2 4.5 22.1 23.2 Mz/Mw (—) ⁶⁾ 3.2 2.6 2.7 6.3 6.3Proportion of high mol. wt. part (%) ⁷⁾ 8 9 1 14 14 S_(H)/S_(L (—)) ⁸⁾1.22 1.21 1.12 1.45 1.44 Melt tension (g) ⁹⁾ 4.8 10.4 1.6 2.3 2.5Critical shearing rate (sec⁻¹) ¹⁰⁾ 1.82 × 10² 6.08 × 10¹ 1.82 × 10³ 1.82× 10³ 1.82 × 10³ Value calculated from formula (I) (—) ¹¹⁾ 7.4 11.9 −2.2−2.2 −2.2 Frexural modulus (MPa) ¹²⁾ 1410 1443 1495 1820 1790 Method ofproduction batch, batch, batch, 2 stage, 2 stage, slurry slurry slurrybatch, cont., slurry slurry

TABLE 12 Comparative Example 1-6 1-7 1-8 1-9 1-10 Polypropylene ResinComposition X-22 X-23 X-24 X-25 X-26 Melt flow rate (g/10 min) ¹⁾ 3.30.5 — 35 0.5 Intri. viscos. of high mol. wt. PP (dl/g) ²⁾ 9.1 3.9 9.4 —7.2 Content of high mol. wt. PP (wt. %) 10 50 100 0 30 Number of gels(per 450 cm²) ³⁾ 15 5 — 2 3320 (mmmm) fraction (%) ⁴⁾ 98.4 98.3 98.398.1 98.1 Mw/Mn (—) ⁵⁾ 18.3 5.5 — 4.9 9.5 Mz/Mw (—) ⁶⁾ 4.5 3.1 — 2.8 3.3Proportion of high mol. wt. part (%) ⁷⁾ 4.5 7 — 1 11 S_(H)/S_(L)(—) ⁸⁾1.41 1.13 — 1.11 1.31 Melt tension (g) ⁹⁾ 3.1 4.6 — — 6.3 Criticalshearing rate (sec⁻¹) ¹⁰⁾ 6.57 × 10² 1.82 × 10² — — 6.08 × 10² Valuecalculated from formula (I) (—) ¹¹⁾ 2.0 7.4 — — 2.3 Frexural modulus(MPa) ¹²⁾ 1632 1433 — — 1652 Method of production 2 stage, 2 stage, 1stage, 1 stage, 2 stage, batch, batch, batch, batch, cont., slurryslurry slurry slurry slurry

TABLE 14 Comparative Example 1-11 1-12 1-13 1-14 Polypropylene ResinComposition X-27 X-28 X-29 X-30 Melt flow rate (g/10 min) ¹⁾ 0.5 0.4 0.50.5 Intri. viscos. of high mol. wt. PP (dl/g) ²⁾ 9.4 10.0 7.1 7.2Content of high mol. wt. PP (wt. %) 30 40 35 55 Number of gels (per 450cm²) ³⁾ 7850 8 7 8 (mmmm) fraction (%) ⁴⁾ 98.2 96.3 96.2 96.1 Mw/Mn (—)⁵⁾ 10.3 38.2 12.4 9.5 Mz/Mw (—) ⁶⁾ 4.1 4.0 3.4 3.3 Proportion of highmol. wt. part (%) ⁷⁾ 14 22 13 20 S_(H)/S_(L) (—) ⁸⁾ 1.46 1.50 1.38 1.24Melt tension (g) ⁹⁾ 10.3 9.2 5.1 8.2 Critical shearing rate (sec⁻¹) ¹⁰⁾1.82 × 10² 6.08 × 10¹ 1.82 × 10² 6.08 × 10¹ Value calculated fromformula (I) (—) ¹¹⁾ 7.4 11.9 7.4 11.9 Frexural modulus (MPa) ¹²⁾ 17231550 1512 1492 Method of production Melt- 2 stage, 2 stage, 2 stage,mixing batch, cont., cont., slurry slurry slurry

<<Blow Molding>>

EXAMPLE 2-1

The polypropylene resin composition X-2 obtained in Example 1-2 wasprocessed by adding thereto a predetermined stabilizer, melting theresulting blend at 230° C. and extruding it using a hollow extruder ofModel NB-20S of The Japan Steel Works, Ltd. into a parison. The weightof the parison was 3 kg. The mold was closed thereafter at once,whereupon compressed air of 0.6 MPa (6 kgf/cm², gauge) was blown intothe inside space of the parison to blow-molding it into a squared blownbottle of 20 liter capacity. No draw-down of parison occurred and themoldability was better. The appearance of the resulting bottle was alsobetter. Results are given in Table 14.

EXAMPLE 2-2

The polypropylene resin composition X-14 obtained in Example 1-14 wasprocessed by adding thereto a predetermined stabilizer, melting theresulting blend at 230° C. and extruding it using a hollow extruder(Plako 3XY-12. Type 15) into a parison. The weight of the parison was 5kg. The mold was closed thereafter at once, whereupon compressed air of0.6 MPa (6 kgf/cm², gauge) was blown into the inside space of theparison to blow-molding it into a spoiler. No draw-down of parisonoccurred and the moldability was better. The appearance of the resultingblow-molded article was also better. Results are given in Table 14.

EXAMPLE 2-3

The polypropylene resin composition X-16 obtained in Example 1-16 wasprocessed by adding thereto a predetermined stabilizer, melting theresulting blend at 240° C. and extruding it using a hollow extruder(Plako 3XY-12. Type 15) into a parison. The weight of the parison was 5kg. The mold was closed thereafter at once, whereupon compressed air of0.6 MPa (6 kgf/cm², gauge) was blown into the inside space of theparison to blow-molding it into a spoiler. No draw-down of parisonoccurred and the moldability was better. The appearance of the resultingblow-molded article was also better. Results are given in Table 14.

Comparative Example 2-1

In the same manner as in Example 2-1, except that polypropylene resincomposition X-17 obtained in Comparative Example 1-1 was employed in theplace of polypropylene resin composition X-2, blow molding of a squaredblown bottle of 20 liter capacity was tried. No blown bottle exhibitingbetter appearance was obtained due to occurrence of draw-down. Resultsare given in Table 14.

Comparative Example 2-2

In the same manner as in Example 2-2, except that polypropylene resincomposition X-18 obtained in Comparative Example 1-2 was employed in theplace of polypropylene resin composition X-14, blow molding of a spoilerwas tried. However, no spoiler exhibiting better appearance was obtaineddue to inferior moldability. Results are given in Table 14.

Comparative Example 2-3

In the same manner as in Example 2-3, except that polypropylene resincomposition X-30 obtained in Comparative Example 1-14 was employed inthe place of polypropylene resin composition X-16, blow molding of aspoiler was tried. No spoiler exhibiting better appearance was obtained.A draw-down of the parison occurred during the blow molding due toinsufficient melt tension of the polypropylene resin composition X-30,so that any spoiler exhibiting better appearance was able to obtain. Thestiffness of the molded article was also insufficient. Results are givenin Table 14.

TABLE 14 Example Moldability *) 2-1 Better 2-2 Better 2-3 Better Comp.2-1 Draw-down of parison occurred Comp. 2-2 Parison had rough surfaceComp. 2-3 Draw-down of parison occurred Note: *) Moldability wasvisually evaluated from the apearance of the molded article

<<Vacuum- and Pressure Forming>>

EXAMPLE 3-1

The polypropylene resin composition X-1 obtained in Example 1-1 wasprocessed by adding thereto a predetermined stabilizer, melting theresulting blend at 230° C. and forming it using a sheet-forming machineModel GS-65 (D=65 mmφ, L/D=28; a machine of Ikegai Iron Works, Ltd.)into a sheet of a thickness of 1.5 mm. This sheet was processed byvacuum forming into a vessel of a form of box having a capacity of 3liters using a vacuum forming machine (a machine of FUSE Vacuum K.K.).No draw-down was recognized during the preheating of the sheet beforeevacuating the machine and the moldability was better. The resultingvacuum-formed article had a uniform wall thickness distribution togetherwith better appearance. Results are given in Table 15.

EXAMPLE 3-2

In the same manner as in Example 3-1, except that polypropylene resincomposition X-6 obtained in Example 1-6 was employed in the place ofpolypropylene resin composition X-1, a sheet was prepared as in Example3-1 and this sheet was processed by vacuum forming into a vessel of aform of box having a capacity of 500 milliliters. No draw-down wasrecognized during the preheating of the sheet before the evacuation andthe moldability was better. The resulting vacuum-formed article had auniform wall thickness distribution with better appearance. Results aregiven in Table 15.

EXAMPLE 3-3

The polypropylene resin composition X-7 obtained in Example 1-7 wasprocessed by adding thereto a predetermined stabilizer, melting theresulting blend at 230° C. and forming it using a sheet-forming machineof GS-65 Type (D=65 mmφ, L/D=28; a machine of Ikegai Iron Works, Ltd.)into a sheet of a thickness of 1.5 mm. This sheet was processed byvacuum forming into a vessel of a form of box having a capacity of 3liters using a pressure forming machine (a machine of FUSE Vacuum K.K.).No draw-down was recognized during the preheating of the sheet and themoldability was better. The resulting vacuum-formed article had auniform wall thickness distribution together with better appearance.Results are given in Table 15.

Comparative Example 3-1

In the same manner as in Example 3-1, except that polypropylene resincomposition X-17 obtained in Comparative Example 1-1 was employed in theplace of polypropylene resin composition X-1, a vacuum forming of abox-formed vessel of 3 liter capacity was tried. However, a draw-down ofthe sheet occurred during the preheating of the sheet directly beforethe evacuation and the moldability was worse. The resultingvacuum-formed article exhibited non-uniform wall thickness distributionand the appearance thereof was also inferior. The results are given inTable 15.

Comparative Example 3-2

In the same manner as in Example 3-2, except that polypropylene resincomposition X-23 obtained in Comparative Example 1-7 was employed in theplace of polypropylene resin composition X-6, a vaccum forming of abox-formed vessel of 500 milliliter capacity was tried. However, adraw-down of the sheet occurred during the preheating of the sheetdirectly before the evacuation and the moldability was worse. Theresulting vaccum-formed article exhibited non-uniform wall thicknessdistribution and the appearance thereof was also inferior. The resultsare given in Table 15.

Comparative Example 3-3

In the same manner as in Example 3-3, except that polypropylene resincomposition X-29 obtained in Comparative Example 1-13 was employed inthe place of polypropylene resin composition X-7, a pressure forming ofa box-formed vessel of 3 liter capacity was tried. However, a draw-downof the sheet occurred during the preheating of the sheet and themoldability was worse. The resulting pressure-formed article exhibitednon-uniform wall thickness distribution and the appearance thereof wasalso inferior. The results are given in Table 15.

TABLE 15 Example Moldability *) 3-1 Better 3-2 Better 3-3 Better Comp.3-1 Draw-down of parison occurred, with non-uniform wall thickness Comp.3-2 Draw-down of parison occurred, with non-uniform wall thickness Comp.3-3 Draw-down of parison occurred, with non-uniform wall thickness Note:*) Moldability was visually evaluated from the appearance of the moldedarticle

<<Foamed Article>>

EXAMPLE 4-1

100 parts by weight of powdered polypropylene resin composition X-6obtained in Example 1-6, 0.1 part by weight of dicumyl peroxide as theorganic peroxide, 1.0 part by weight of divinylbenzene as the crosslinking co-agent, 4 parts by weight of azodicarbonamide as the foamingagent, 0.2 parts by weight of an antioxidant and 0.2 parts by weight ofa heat stabilizer were blended on a high-speed mixer (Henschel mixer ofMitsui Miike Seisakusho K.K.) to obtain a foamable composition forforming into sheet. This composition was then granulated through anextruder of 65 mmφ into a pelletized product. The resin temperaturetherefor was 170° C. The so-pelletized product was supplied to asheet-forming machine GS-65 Type of Ikegai Iron Works, Ltd. (D=65 mmφ,L/D=28, lip opening width 1.0 mm) to process into a foamablepolypropylene sheet. The sheet-forming temperature was 170° C. and nofoaming was found during the sheet-forming. The resulting sheet had athickness of 1.0 mm.

The resulting foamable polypropylene sheet was heated by a ceramicheater in the vacuum forming machine for about 90 seconds to blow upinto a foamed polypropylene sheet. The temperature of the ceramic heaterwas settled at 400° C. and the superficial temperature of the formablepolypropylene sheet was 210° C. The resulting foamed sheet was cooled byair spray for 60 seconds. The so-obtained foamed polypropylene sheet hada thickness of about 11.9 mm and a density of 0.08 g/cm³ and the foamingmagnification ratio was about 11.9-fold. For this foamed polypropylenesheet, the following evaluations were carried out, of which results aregiven in Table 16.

[Evaluation of Foamed Sheet]

(1) Foaming Magnification Ratio

The foaming magnification ratio was represented by the ratio of thefoamed sheet thickness to the original foamable sheet thickness. Thethickness was determined using slide calipers.

(2) State of Foaming

The cell structure observed on a cut face of the foamed sheet wasvisually evaluated based on the following criterion:

⊚ Fine uniform cell structure

∘ Uniform cell structure

Δ Non-uniform cell structure with coarse cells

× Inferior foaming.

(3) Cell Size

Cell diameter was determined from microphotograph.

Example 4-2

In the same manner as in Example 4-1, except that polypropylene resincomposition X-5 obtained in Example 1-5 was used instead of thepolypropylene resin composition X-6, a foamed polypropylene sheet wasproduced. Evaluation of the resulting sheet was performed in the samemanner as in Example 4-1. Results are given in Table 16.

EXAMPLE 4-3

In the same manner as in Example 4-1, except that polypropylene resincomposition X-5 obtained in Example 1-5 was used instead of thepolypropylene resin composition X-6 and that 15 parts by weight of glassfibers were admixed thereto, a foamed polypropylene sheet was produced.Evaluation of the resulting sheet was performed in the same manner as inExample 4-1. Results are given in Table 16.

EXAMPLE 4-4

100 parts by weight of powdered polypropylene resin composition X-11obtained in Example 1-11, 0.2 parts by weight of an antioxidant and 0.2parts by weight of a heat stabilizer were blended on a high-speed mixer(Henschel mixer, supplied from Mitsui Miike Seisakusho K.K.) to obtain afoamable composition for forming into polypropylene sheet. To thiscomposition was then added 0.1 part by weight of sodium bicarbonateserved as the foaming nucleating agent and the mixture was kneaded on anextruder of 65 mmφ, while supplying thereto carbon dioxide as thefoaming agent at a portion midway the cylinder to produce a foamedpolypropylene sheet. The resulting foamed sheet had a thickness of 5.0mm. By calculating based on the density (0.91 g/cm³) of the originalnon-foamed sheet, the foaming magnification ratio was 5-fold. Theevaluation of this foamed polypropylene sheet was performed in the samemanner as in Example 4-1. Results are given in Table 16. By the way, thecell size was found to be in the range of 50-200 μm, of which averagevalue was 100 μm.

EXAMPLE 4-5

100 parts by weight of powdered polypropylene resin composition X-1lobtained in Example 1-11, 0,2 parts by weight of an antioxidant, 0.2parts by weight of a heat stabilizer and 20 parts by weight of a lowdensity polyethylene product (MIRASON B319, trademark, a product ofMitsui Chemicals, Inc.) were blended on a high-speed mixer (Henschelmixer supplied from Mitsui Miike Seisakusho K.K.) to obtain a foamablecomposition for forming into a propylene sheet. Using this composition,a foamed polypropylene sheet was obtained in the same manner as inExample 4-4. The evaluation of the so-obtained foamed polypropylenesheet was performed in the same manner as in Example 4-1. Results aregiven in Table 16.

Comparative Example 4-1

In the same manner as in Example 4-1, except that the polypropylene X-17obtained in Comparative Example 1-1 was used instead of thepolypropylene resin composition X-6, a foamed polypropylene sheet wasproduced. For the resulting polypropylene foamed sheet, evaluations werecarried out in the same manner as in Example 4-1. Results are given inTable 16.

Comparative Example 4-2

In the same manner as in Example 4-1, except that the polypropyleneresin composition X-19 obtained in Comparative Example 1-3 was usedinstead of the polypropylene resin composition X-6, a foamedpolypropylene sheet was produced. For the resulting polypropylene foamedsheet, evaluations were carried out in the same manner as in Example4-1. Results are given in Table 16.

Comparative Example 4-3

In the same manner as in Example 4-1, except that the polypropyleneresin composition X-19 obtained in Comparative Example 1-3 was usedinstead of the polypropylene resin composition X-6 and that 15 parts byweight of GF (glass fiber) were further admixed thereto, production offoamed polypropylene sheet was tried. However, by escape of the gasgenerated from the foaming agent due to collapse of foam cells by theglass fibers, any foamed sheet was not able to obtain.

Comparative Example 4-4

In the same manner as in Example 4-4, except that the polypropyleneresin composition X-17 obtained in Comparative Example 1-1 was usedinstead of the polypropylene resin composition X-11, a foamedpolypropylene sheet was produced. For the resulting polypropylene foamedsheet, evaluations were carried out in the same manner as in Example4-1. Results are given in Table 16.

Comparative Example 4-5

100 parts by weight of powdered polypropylene resin composition X-17obtained in Comparative Example 1-1, 0.2 parts by weight of anantioxidant, 0.2 parts by weight of a heat stabilizer and 20 parts byweight of a low density polyethylene (MIRASON B319, trademark, a productof Mitsui Chemicals, Inc.) were kneaded on a high-speed Henschel mixer(supplied from Mitsui Miike Seisakusho K.K.) to obtain a composition forforming a foamable polypropylene sheet. This composition was caused toblow up into a foamed polypropylene sheet in the same manner as inExample 4-4. For the resulting foamed polypropylene sheet, evaluationswere carried out in the same manner as in Example 4-1. Results are givenin Table 16.

TABLE 16 Properties of Foamed Sheet Glass Foaming fiber Sheet magnif.Example cont. cell Cell size rate Density No. (wt. %) structure (μm)(times) g/cm³ Ex. 4-1 0 ⊚ 300˜700 11.9 0.08 Comp. 4-1 0 Δ 1000˜1500 3.10.29 Ex. 4-2 0 ⊚ 300˜700 10.5 0.09 Comp. 4-2 0 Δ 1000˜1500 2.8 0.29 Ex.4-3 15 ◯ 300˜700 10.1 0.13 Comp. 4-3 15 x not formable — 0.92 Ex. 4-4 0⊚  50˜200 5.0 0.18 Comp. 4-4 0 Δ 100˜500 1.6 0.58 Ex. 4-5 0 ⊚  50˜2006.3 0.16 Comp. 4-5 0 Δ 100˜500 1.9 0.50

<<Calendered Article>>

EXAMPLE 5-1

The polypropylene resin composition X-12 obtained in Example 1-12 wasprocessed, after addition thereto a predetermined stabilizer, bycalendering using a calendering machine (a reverse L-formed machinesupplied from Nippon Roll K.K.) at a resin temperature of 220° C., afirst roller temperature of 175° C., a second roller temperature of 175°C., a third roller temperature of 175° C., a fourth roller temperatureof 175° C. and a cooling roller temperature of 80° C., at a rolling-upspeed of 40 m/sec to form a sheet having a thickness of 2 mm. Nodraw-down was observed during the processing and the moldability wasbetter. Results are given in Table 17.

EXAMPLE 5-2

The polypropylene resin composition X-3 obtained in Example 1-3 wasprocessed, after addition thereto a predetermined stabilizer, bycalendering using a calendering machine (a reverse L-formed machinesupplied from Nippon Roll K.K.) at a resin temperature of 230° C., afirst roller temperature of 180° C., a second roller temperature of 180°C., a third roller temperature of 180° C., a fourth roller temperatureof 180° C. and a cooling roller temperature of 80° C., at a rolling-upspeed of 40 m/sec to form a sheet having a thickness of 2 mm. Nodraw-down was observed during the processing and the moldability wasbetter. Results are given in Table 17.

EXAMPLE 5-3

The polypropylene resin composition X-7 obtained in Example 1-7 wasprocessed, after addition thereto a predetermined stabilizer, bycalendering using a calendering machine (a reverse L-formed machinesupplied from Nippon Roll K.K.) at a resin temperature of 240° C., afirst roller temperature of 190° C., a second roller temperature of 190°C., a third roller temperature of 190° C., a fourth roller temperatureof 190° C. and a cooling roller temperature of 80° C., at a rolling-upspeed of 40 m/sec to form a sheet having a thickness of 2 mm. Nodraw-down was observed during the processing and the moldability wasbetter. Results are given in Table 17.

Comparative Example 5-1

In the same manner as in Example 5-1 except that the polypropylene resincomposition X-19 obtained in Comparative Example 1-3 was used instead ofthe polypropylene resin composition X-12, calendering of sheet wastried. However, a draw-down occurred during the calendering andproduction of sheet failed. Results are given in Table 17.

Comparative Example 5-2

In the same manner as in Example 5-2 except that the polypropylene resincomposition X-23 obtained in Comparative Example 1-7 was used instead ofthe polypropylene resin composition X-3, calendering of sheet was tried.However, a draw-down occurred during the calendering and production ofsheet failed. Results are given in Table 17.

Comparative Example 5-3

In the same manner as in Example 5-3 except that the polypropylene resincomposition X-26 obtained in Comparative Example 1-10 was used insteadof the polypropylene resin composition X-7, calendering of sheet wastried. However, a draw-down occurred during the calendering andproduction of sheet failed. Results are given in Table 17.

TABLE 17 Example Moldability *) 5-1 Better 5-2 Better 5-3 Better Comp.5-1 Draw-down occurred Comp. 5-2 Draw-down occurred Comp. 5-3 Draw-downoccurred with gel-formation Note: *) Moldability was visually evaluatedfrom the appearance of the sheet.

<<Extrusion-molded Articles>>

EXAMPLE 6-1

The polypropylene resin composition X-4 obtained in Example 1-4 wasprocessed, after addition thereto a predetermined stabilizer, byextrusion-molding using a pipe molding machine of Model FS-65 of IkegaiIron Works, Ltd. (D=65 mmφ, L/D=25) at a resin temperature of 220° C.into a pipe having a diameter of 90 cm with a wall thickness of 1.5 mm.No draw-down occurred during the molding and the moldability was better.Results are given in Table 18.

EXAMPLE 6-2

The polypropylene resin composition X-15 obtained in Example 1-15 wasprocessed, after addition thereto a predetermined stabilizer, byextrusion-molding using a sheet extruding machine of Model FS-65 ofIkegai Iron Works, Ltd. (D=65 mmφ, L/D=25) at a resin temperature of220° C. into a sheet of a thickness of 2 mm. No draw-down occurredduring the molding and the moldability was better. Results are given inTable 18.

EXAMPLE 6-3

In the same manner as in Example 6-1 except that the polypropylene resincomposition X-10 obtained in Example 1-10 was used instead of thepolypropylene resin composition X-4, extrusion molding of pipe wascarried out. No draw-down occurred during the molding and themoldability was better. Results are given in Table 18.

Comparative Example 6-1

In the same manner as in Example 6-1 except that the polypropylene resincomposition X-17 obtained in Comparative Example 1-1 was used instead ofthe polypropylene resin composition X-4, extrusion molding of pipe wascarried out. However, a draw-down occurred during the molding andproduction of pipe failed. Results are given in Table 18.

Comparative Example 6-2

In the same manner as in Example 6-2 except that the polypropylene resincomposition X-23 obtained in Comparative Example 1-7 was used instead ofthe polypropylene resin composition X-15, extrusion molding of sheet wascarried out. However, a draw-down occurred during the molding andproduction of sheet failed. Results are given in Table 18.

Comparative Example 6-3

In the same manner as in Example 6-1 except that the polypropylene resincomposition X-28 obtained in Comparative Example 1-12 was used insteadof the polypropylene resin composition X-4, extrusion molding of pipewas carried out. However, due to insufficient plasticizing of the highermolecular weight polymers and the lower molecular weight polymers owingto the wide molecular weight distribution of the polypropylene resincomposition X-17, the appearance of the resulting molded product wasworse and, in addition, the stiffness thereof was inferior due to lowerisotactic pentad fraction. Results are given in Table 18.

TABLE 18 Results of Extrusion Molding Example Moldability *) 6-1 Better6-2 Better 6-3 Better Comp. 6-1 Draw-down of pipe occurred Comp. 6-2Draw-down of sheet occurred Comp. 6-3 Rough surface occurred withinsufficient stiffness Note: *) Moldability was visually evaluated fromthe appearance of the sheet.

<<Stretched Film>>

EXAMPLE 7-1

The polypropylene resin composition X-13 obtained in Example 1-13 wasblended with a predetermined stabilizer on a Henschel mixer and theresulting blend was processed by a 65 mmφ monoaxial extruder (a machinesupplied from Ishinaka Tekkosho K.K.) into a pelletized product. Thepelletized product was processed by extruding from a sheet-formingmachine having an aperture diameter of 90 mm at a resin temperature of280° C. and passing through a cooling roller at 30° C. into a sheet of1.5 mm thickness. The so-obtained sheet was subjected to a stretching ona tenter-type successive biaxial stretching machine at 145° C. at astretching ratio in the longitudinal direction of 5-fold and then10-fold in the lateral direction in a tenter of a vessel temperature of170° C. to obtain a biaxially stretched film having a thickness of about30 μm. Here, the film processing speed was able to increase up to 45m/min. The thickness accuracy of the so-obtained film was visuallyevaluated. Results are given in Table 19.

Example 7-2

In the same manner as in Example 7-1 except that the polypropylene resincomposition X-9 obtained in Example 1-9 was used instead of thepolypropylene resin composition X-13, a biaxially stretched film of athickness of 30 μm was obtained. Results are given in Table 19.

Comparative Example 7-1

In the same manner as in Example 7-1 except that the polypropylene resincomposition X-19 obtained in Comparative Example 1-3 was used instead ofthe polypropylene resin composition X-13, production of a biaxiallystretched film of 30 μm thickness was tried. However, due to the lowerthickness accuracy of the original roll sheet causing thinner area inthe center of film, breaking of film occurred during the stretching andstable production of film was not able. Results are given in Table 19.

Comparative Example 7-2

In the same manner as in Example 7-1 except that the polypropylene resincomposition X-27 obtained in Comparative Example 1-11 was used insteadof the polypropylene resin composition X-13, a biaxially stretched filmof 30 μm thickness was produced. However, considerable gel-formationoccurred, whereby the appearance of the film as a biaxially stretchedfilm was debased greatly. Results are given in Table 19.

TABLE 19 Results of Stretching of Film Maximum Thickness Example filmspeed accuracy *) 7-1 45 m/min. ⊚ 7-2 40 m/min. ⊚ Comp. 7-1 notstrechable x Comp. 7-2 40 m/min. Considerable gel-formation Note: *)visually evaluated by the criterion: ⊚: Better thickness accuracy withuniform film thickness ◯: Somewhat debased thickness accuracy withoccurrence of thickness irregularity on a part of the film Δ: Inferiorthickness accuracy with thinning in central portion of the film, yetpermitting stretching x: Bad thickness accuracy with thinning in centralportion of film, with occurrence of film breaking

<<Inflation Film>>

EXAMPLE 8-1

The polypropylene resin composition X-8 obtained in Example 1-8 wasblended with a predetermined stabilizer and the resulting blend wasprocessed by a 65 mmφ single screw extruder into a pelletized product.The pelletized product was processed by an inflation molding using acommercially available tubular film producing machine for polyolefininto a film having a width of 180 mm and a thickness of 0.03 mm. Themolding was effected at a resin temperature of 230° C. and at a screwrevolution rate of 60 r.p.m. with a die of 60 mmφ diameter and 0.3 mmslit width and with a single stage air cooling (air temperature of 10°C.). The resulting inflation film was tested for its Young's modulusaccording to ASTM D-882 and for its haze in accordance with ASTM D-1003.Results are given in Table 20.

EXAMPLE 8-2

In the same manner as in Example 8-1 except that the polypropylene resincomposition X-12 obtained in Example 1-12 was used instead of thepolypropylene resin composition X-8, an inflation molding of film wasperformed. Results are given in Table 20.

Comparative Example 8-1

In the same manner as in Example 8-1 except that the polypropylene resincomposition X-19 obtained in Comparative Example 1-3 was used instead ofthe polypropylene resin composition X-8, an inflation molding of filmwas performed. Results are given in Table 20.

Comparative Example 8-2

In the same manner as in Example 8-1 except that the polypropylene resincomposition X-22 obtained in Comparative Example 1-6 was used instead ofthe polypropylene resin composition X-8, an inflation molding of filmwas performed. Results are given in Table 20.

Comparative Example 8-3

In the same manner as in Example 8-1 except that the polypropylene resincomposition X-20 obtained in Comparative Example 1-4 was used instead ofthe polypropylene resin composition X-8, an inflation molding of filmwas performed. Results are given in Table 20.

Comparative Example 8-4

In the same manner as in Example 8-1 except that the polypropylene resincomposition X-21 obtained in Comparative Example 1-5 was used instead ofthe polypropylene resin composition X-8, an inflation molding of filmwas performed. Results are given in Table 20.

TABLE 20 Results of Film Inflation Molding Young's Stability Hazemodulus of Example (%) (kgf/cm²) baloon *) 8-1 9.2 154 ◯ 8-2 8.6 148 ◯Comp. 8-1 10.3 108 x Comp. 8-2 9.8 119 Δ Comp. 8-3 10.5 142 x Comp. 8-410.1 135 x Note: *) By the following evaluation criterion: ◯: Stablebaloon with uniform film thickness Δ: Unstable baloon with irregularfilm thickness x: Unstable baloon with impermission of continuousmolding

EXAMPLE 9-1

Using the polypropylene resin composition X-2 obtained in Example 1-2, aparison was extrusion-molded at a resin temperature of 210° C. Thisparison was worked once by a pre-blowing by blowing air into the insidespace of the parison and was then set in a split mold to process it byblow molding under the condition given below by blowing air thereinto.No draw-down of the parison occurred and the moldability was better. Theappearance of the molded article was better and no rough surface norwaving was observed.

Mirror reflection degree #1500 of mold cavity face Air vents 0.3 mm φ,at 50 mm pitch Resin temperature on 210° C. blow molding Pressure ofblown air 490 kPa

EXAMPLE 9-2

In the same manner as in Example 9-1 except that the polypropylene resincomposition X-10 obtained in Example 1-10 was used instead of thepolypropylene resin composition X-2, a blow molding was performed.Results are given in Table 24.

Comparative Examples 9-1 to 9-4

In the same manner as in Example 1-2 except that the polymerizationcondition was changed to those given in Table 21 below, polypropyleneresin compositions were produced. Then, using each of these resincompositions in the place of the polypropylene resin composition X-2,blow molding was performed in the same manner as in Example 9-1. Resultsare given in Tables 22-24.

TABLE 21 In lst stage polymer. In 2nd stage polymer. H₂- H₂- part. part.Comp. Temp. Durat. press. Temp. Durat. press. Example (° C.) (min.)(kPa) (° C.) (min.) (kPa) 9-1 70 60 9.8 — — — 9-2 70 60 7.8 — — — 9-3 6035 — 70 35 78 9-4 60 35 — 70 20 69

TABLE 22 [η] of Content of high mol. high mol. Comp. MFR ¹⁾ (mmmm) wt.component wt. component Example (g/10 min) (%) ²⁾ (dl/g) ³⁾ (wt. %) 9-10.5 97.5 — 0 9-2 0.2 98.2 — 0 9-3 0.5 98.2 10 40 9-4 0.3 98.2 9.5 48Notes: ¹⁾ MFR was determined according to ASTM D1238. ²⁾ Isotacticpentad fraction, determined by ¹³C-NMR. ³⁾ Intrinsic viscosity [η],determined in decalin at 135° C.

TABLE 23 Critical Calcu- Melt shearing lation by Comp. tension rate ⁴⁾formula Example Mw/Mn ¹⁾ Mz/Mw ²⁾ (g) ³⁾ (sec⁻¹) (I) ⁵⁾ 9-1 4.9 3.2 5.61.824 × 10² 7.342 9-2 4.2 2.6 10.4 6.080 × 10¹ 11.91 9-3 32.4 4.4 12.56.080 × 10⁰ 21.49 9-4 7.5 4.1 11.4 6.080 × 10¹ 11.91 Notes: ¹⁾Determined by GPC. ²⁾ Determined by GPC. ³⁾ Determined under thefollowing conditions: Apparatus : CAPIROGRAPH 1C (trademark) of ToyoSeiki Seisaku-Sha, Ltd. Temperature : 230° C. Orifice : L = 8.00, D =2.095 mm Extrusion speed : 15 mm/min. Rolling-up speed : 10 m/min. 4)The shearing speed at which melt fracture is brought about is determinedunder the following conditions: Apparatus : CAPIROGRAPH 1C (trademark)of Toyo Seiki Seisaku-Sha, Ltd. Temperature : 230° C. Orifice : L =10.9, D = 1.00 mm 5) Values calculated from the numerical formula (I)given previously.

TABLE 24 Frexural modulus Moldability Example (MPa) ¹⁾ (appearance) ²⁾9-1 1716 Better 9-2 1700 Better Comp. 9-1 1422 Draw-down of parisonComp. 9-2 1568 Rough surface on parison Comp. 9-3 1720 Rough surface onparison Comp. 9-4 1754 Rough surface on parison Notes: ¹⁾ Determinedaccording to ASTM D790. ²⁾ “Better” means that the parison is superiorin the appearance with no draw-down nor surface roughness nor waving.

As seen from Table 24, the polypropylene resin compositions of Examples9-1 and 9-2 which have the characteristic features of 1), 2), 4), 5), 7)and 8) defined in claim 8 are superior in the stiffness (frexuralmodulus) and moldability.

In contrast, the polypropylene resin of Comparative Example 9-1 whichhas a single-modal molecular weight and low isotactic pentad fractionhas a low stiffness and brings about molded articles of inferiorappearance. The polypropylene resin of Comparative Example 9-2 which hasa single-modal molecular weight and a higher isotactic pentad fractionhas a low stiffness and brings about molded articles of somewhatinferior appearance, though it exhibits an improved melt tension. Thepolypropylene resin composition of Comparative Example 9-3 which has abi-modal molecular weight distribution and is wider in the Nw/Mn-valuebrings about molded articles of inferior appearance, though it has animproved melt tension and increased stiffness. The polypropylene resincomposition of Comparative Example 9-4 which possesses thecharacteristic features 1), 2), 4), 5), 7) and 8) defined in claim 8 butdoes not meet the condition of formula (I) brings about molded articlesof somewhat inferior appearance, though it has an improved melt tensionand increased stiffness.

INDUSTRIAL APPLICABILITY

As described above, the first and the second polypropylene resincompositions according to the present invention have a high melt tensionand are superior in the moldability and stiffness and can bring aboutmolded articles, which are superior in the appearance and aredifficultly deformable, at a high through-put rate in an efficientmanner, even in the case of large-sized articles. Therefore, thepolypropylene resin composition according to the present invention willfind wide applications in application fields requiring the aboveidentified characteristic features without limitation. It can be used asthe starting materials for, such as blow-molded articles, vacuum- orpressure-formed articles, calendered articles, extrusion-moldedarticles, stretched films, inflation films and foamed articles,favoritely. By the process for producing the polypropylene resincomposition according to the present invention, the above-mentionedpolypropylene resin composition according to the present invention caneasily and efficiently be produced at a low cost.

The resin composition for blow molding according to the presentinvention has a high melt tension and is superior in the moldability andin the stiffness due to the content of the polypropylene resincomposition according to the present invention, and therefore, can beused favoritely as the starting material for blow molding large-sizedand difficultly deformable articles in high-speed molding.

The blow-molded articles according to the present invention canencompass wide variety of articles, including, due to the superiorappearance and higher stiffness, larger automobile exterior parts, suchas bumper and spoiler, and large-sized bolts etc.

The vacuum- and pressure-formed articles, calendered articles, extrusionmolded articles, stretched films and inflation films according to thepresent invention are superior, due to the use of the polypropyleneresin composition according to the present invention as their material,in the appearance and in the stiffness, so that they can includearticles necessitating the above-mentioned characteristic features.

The foamed articles according to the present invention exhibit a highfoaming magnification ratio and have uniform foam cell structure of finecells, so that their use, in particular, for large-sized articles willfavor the user.

What is claimed is:
 1. A polypropylene resin composition comprisingpolypropylene as a main component, said polypropylene resin compositionhaving the characteristic features: 1) a melt flow rate (MFR),determined at 230° C. under a load of 2.16 kg, in the range of 0.01-5g/10 min, 2) a content of a high molecular weight polypropyleneexhibiting an intrinsic viscosity (η), determined at 135° C. in decalin,of 8-13 dl/g in the range of 15-50% by weight, 3) a gel areal density innumber of 3,000/450 cm² or less, and 4) a molecular weight distribution,determined by gel permeation chromatography (GPC), in the range of 6-20for Mw/Mn and 3.5 or higher for Mz/Mw.
 2. The polypropylene resincomposition according to claim 1, wherein said polypropylene resincomposition has the further characteristic feature: 5) an isotacticpentad fraction (mmmm fraction), determined by ¹³C-NMR, of at least 97%.3. The polypropylene resin composition according to claim 1, whereinsaid polypropylene resin composition has the further characteristicfeature: 6) when dividing an area underlying a molecular weightdistribution curve on a molecular weight distribution diagram, obtainedby gel permeation chromatography, at the maximum peak molecular weightinto two parts, a ratio of the surface area, S_(H), for the highermolecular weight side part to the surface area, S_(L), for the lowermolecular weight side part, S_(H)/S_(L), is at least 1.3; and aproportion of the area for the high molecular weight part having amolecular weight of at least 1.5×10⁶ relative to the surface areaunderlying the entire molecular weight distribution curve is at least7%.
 4. The polypropylene resin composition according to claim 2, whereinsaid polypropylene resin composition has the further characteristicfeature: 6) when dividing an area underlying a molecular weightdistribution curve on a molecular weight distribution diagram, obtainedby gel permeation chromatography, at the maximum peak molecular weightinto two parts, a ratio of the surface area, S_(H), for the highermolecular weight side part to the surface area, S_(L), for the lowermolecular weight side part, S_(H)/S_(L), is at least 1.3; and aproportion of the area for the high molecular weight part having amolecular weight of at least 1.5×10⁶ relative to the surface areaunderlying the entire molecular weight distribution curve is at least7%.
 5. The polypropylene resin composition according to claim 1, whereinsaid polypropylene resin composition has the further characteristicfeature: 7) a melt tension (MT), determined by flow tester at 230° C.,is in the range of 5-30 g.
 6. The polypropylene resin compositionaccording to claim 2, wherein said polypropylene resin composition hasthe further characteristic feature: 7) a melt tension (MT), determinedby flow tester at 230° C., is in the range of 5-30 g.
 7. Thepolypropylene resin composition according to claim 3, wherein saidpolypropylene resin composition has the further characteristic feature:7) a melt tension (MT), determined by flow tester at 230° C., is in therange of 5-30 g.
 8. The polypropylene resin composition according toclaim 4, wherein said polypropylene resin composition has the furthercharacteristic feature: 7) a melt tension (MT), determined by flowtester at 230° C., is in the range of 5-30 g.
 9. A process for producinga polypropylene resin composition as claimed in claim 1, by polymerizingpropylene in a multistage polymerization of at least two stages in thepresence of a polymerization catalyst formed from (a) a solid catalystcomponent based on titanium containing magnesium, titanium, a halogenand an election donor, (b) a catalyst component based on anorganometallic compound and (c) a catalyst component based on anorganosilicon compound having at least one group selected from the groupconsisting of cyclopentyl, cyclopentenyl, cyclopentadienyl andderivatives thereof; the said process comprising: forming, in a firstpolymerization stage, a high molecular weight polypropylene producthaving an intrinsic viscosity (η), determined at 135° C., in decalin, of8-13 dl/g, up to a proportion of 15-50% by weight with respect to thetotal amount of the finally obtained polypropylene resin composition, bypolymerizing propylene in the substantial absence of hydrogen; and then,in each of a second and any succeeding polymerization stages,polymerizing propylene in such a manner that a polypropylene producthaving an intrinsic viscosity (η), determined at 135° C. in decalin,lower than 8 dl/g is produced and that the melt flow rate (MFR),determined at 230° C. under a load of 2.16 kg, of the finally obtainedpolypropylene resin composition will, as a whole, be in the range of0.01-5 g/10 min.
 10. The process as claimed in claim 9, wherein thepolymerization of propylene in each polymerization stage is effectedcontinuously.
 11. The process as claimed in claim 9, wherein thepolymerization of propylene in said second and any succeedingpolymerization stages is effected using at least two polymerizationreactors.
 12. A blow-molded article produced by subjecting the resincomposition defined in claim 1 to the blow molding.
 13. A vacuum-formedor pressure-formed article produced by subjecting the polypropyleneresin composition defined in claim 1 to a vacuum or pressure forming.14. A calendared article produced by subjecting the polypropylene resincomposition defined in claim 1 to a calendaring.
 15. A foamed articleproduced by subjecting the polypropylene resin composition defined inclaim 1 to foaming.
 16. An extrusion-molded article produced bysubjecting the polypropylene resin composition defined in claim 1 to anextrusion molding.
 17. A stretched film produced by subjecting a sheetor film of the polypropylene resin composition defined in claim 1 to astretching.
 18. An inflation film produced by subjecting thepolypropylene resin composition defined in claim 1 to an inflationmolding.